Hi everyone. My questions are a bit different to the usual transfer advice, so please bear with me while I explain (and apologies for not using the suggested post format)
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1. I arrive HND on Friday morning. Scheduled arrival is 5:15am but often is earlier, sometimes as early as 4:30am.
   How long does it typically take to get through immigration & customs at that time in the morning? (I'm traveling in business and should be one of the first off the plane if that matters, I also will have one suitcase in checked luggage).
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2. My flight from NRT is at 6:30pm, so I have plenty of time to transfer. My preference is go via train and I have found via the "Access Wayfinding" link a through service (same train) that leaves at 6:37am from the international terminal. If the flight arrives on time, do you think I would be able to make it to the train on time?
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3. I plan to buy either a PASMO or Suica card at the airport train station. Which one would be better to get? (I will use the card for a few days when I return to Tokyo in a few weeks).
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4. With pretty much a whole day to kill once I've checked in at NRT for my flight, is it worth taking a trip from the airport to somewhere nearby? I thought I might go to the Aeon Mall, but perhaps there is something a bit more interesting to do.

Probably 30 to 45 minutes. But it can vary if, for example, your flight lands after another early flight.

Yes. But you might prefer to break your journey in Tokyo since you have time to kill.

PASMO, because
(1) If you take the through train, you'll be departing from the Keikyu station, where you can buy PASMO
(2) The deposit on a SUICA card issued by the Monorail company is only refundable at Monorail stations - not ordinary JR stations. (The stored value on the card is refundable at any JR station, subject to a modest transaction fee)

I would advise breaking your journey to the airport to spend some time in Tokyo. You can put luggage in a coin locker somewhere and pick it up before catching your onward train.
If you really want to go to NRT at silly-o'clock in the morning, I recommend that you confirm in advance that your airline will allow you to check luggage at that hour. After you have deposited your luggage, you could catch a train to Narita City and explore the temple and its gardens, visit an onsen, see the Aeon mall (oooh!), and eat some eel. Or you could go to Tokyo.

As above, breaking the journey up is what I would do if it was me. And then I would be sad that I didn't have more time in Tokyo, but that's a digression.

I was trying to think of arguments or scenarios _against_ breaking up the journey since I am hesitant to give strangers absolute unqualified advice.

The best (only) reason I could come up with is if [MENTION=525]mgm[/MENTION] doesn't want to deal with figuring out intra-tokyo transportation with luggage in tow. With MGM's plan, he has exactly one train to find/deal with before his luggage is dropped off. Just in case that's the driving factor, I want to chime in that there are some transportation options that keep almost all of the simplicity and still allow for a leisurely stop in Tokyo. For example, limo bus Haneda to Shinjuku, locker for luggage, wander the area, limo bus Shinjuku to Narita. Lots of options.

If you really want to go directly to Narita, I highly recommend taking the bus from Haneda. That time of day is rush hour, and the trains are going to very crowded and not comfortable. And quite a nuisance with luggage.

As others said, maybe find a location in central Tokyo to store your luggage and spend a few hours there. This will of course get you in to some rush hour flow, but the time spent will be so much nicer than in Narita and surroundings. :)

Wouldn't that early train would be pre-rush?

It will not be the worst possible crush hour, but it is going to be very busy.

Thanks for the feedback everyone.

I've done the bus trip from HND to NRT before, during the afternoon, and frankly found it incredibly long and tedious. My thoughts on taking the train would be that it should be pretty much straightforward, guaranteed to arrive at the scheduled time and be somewhat more interesting given the variety of stops along the way (not everyone's cup of tea I realise). Of course, the possibility of a morning crush is not good but I thought I might just miss it with the train I was looking at.

I might rethink my plan and look at heading to somewhere in Tokyo, store luggage and do a bit of exploring.

Thanks again.

Agree with heading to Tokyo and storing luggage, wander around a bit, then going to NRT.
Even large suitcase size lockers are likely to be available in large stations early in the morning.
If not, there's this place:

• The airport(s) at which you are transiting NARITA to HANEDA
• The airline on which you are arriving AIR CANADA
• The airline on which you are departing ANA
• Your connection time in hours/minutes 3 HOURS
• How you are connecting, whether international to international (Int-Int), international to domestic (Int-Dom), domestic to international (Dom-Int), or domestic to domestic (Dom-Dom) INTERNATIONAL - DOMESTIC
• Whether you are traveling on a single ticket, or separately-booked tickets SINGLE TICKET

My son and his significant are travelling from Montreal (AC) to Narita and then transfer to Haneda for a domestic flight with ANA to Miyazaki. The AC flight arrives at 3:50PM and the ANA flight departs at 6:50PM. Given the land transfers between the two airports it seems like this will be tight but it is a valid routing per AC. The advice they have been given is that the bus transfer is the route to go as it takes less time (normally) and is a direct route to Haneda compared to multiple train stops. They will have several bags as they are taking up residence. So there will be some time taken at Immigration (she has a Japanese passport). His paper work has been meticulously prepared but there is always the potential for issues to arise. I am looking for FT insights, advice and past experience with this type of transfer. Thx.

If he is taking up residence, his residence card will be issued in the airport and immigration does take extra time. Based on this, I will say 3 hours is not enough. It is a quite tight run to begin with and extra immigration time can quickly make it impossible.
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Do they also have moving boxes shipped separately? As that can add to the time at customs as well.

Overall, I would look for a longer connection.

+1

No they will have everything with them.

I thought that it might be tight. At this point, their only option is to overnight in Haneda and catch the next flight in the morning. Where this was an authorized connection from AC they would be protected on the next ANA flight?

yes they should be.

Just thought that I should update the discussion with the actual results. There was an ANA representative waiting for my son at immigration and facilitated the process. Apparently it took only 10 minutes to get processed. I didn't get all of the details from him but the last we heard from him was that he was sitting on the ANA flight getting ready to leave for Miyazaki. He was impressed with ANA and the Japanese officials.

Thanks for the input above.

Glad to hear it!