Same day upgrades can be purchased at any airport counter.
So, if you have HND-OKA-HND, you can purchase both of upgrades at HND from 05:15AM.
Other domestic airport counters open later, so ex-HND flyers have advantage for sameday upgrades.
(Sometimes, this is critical for mileage runners )

However, you can request waitlist for upgrades at only departing airport.
In above case, if OKA-HND's premium class is full, still you can request waitlist, but you have to make this request at OKA. This request can be done at checkin counter, or airside (after security check) service counters.

I could not find the corresponding English page about waitlisting.
http://www.ana.co.jp/dom/checkin/service/vacant.html
star-G members have priority for waitlisting (same priority catergory of NH own diamond members)