Time from Plane to DB at DUS
 

Arriving at DUS on LH from MUC at 1140 with a checked bag on a Friday morning, what is earliest I could catch a train assuming everything is on time? Looking to travel to Bielefeld in 1st class and saw a train at1309. I will buy the most flexible ticket just in case. First time at DUS and on DB! Thanks :-)

To join the S Bahn station Flughafen Bf from DUS airport, you need to take a Skytrain, a small monorail linking the airport to the station, it is frequent (every 5 minutes) and takes 5 minutes. It is not a free shuttle.Be aware you need a ticket for that, and it is highly possible your train ticket does not include the sky train.
Right now the biggest unknown are baggage delivery, they tend to be longer than usual. If you take a flexpreis then do not worry.

Thanks so much for the info! I did purchase flexpreis for the 1309 departure.

I can't see any trains at 1309 for upcoming Fridays. What date is this for?

Are you flying into MUC? If not I would rather take a train all the way from Munich - and personally I don't think first class is worth it for a 1.5 hour journey (while it might be for a 6.5 hour journey) especially when the 9 euro ticket is available and an ICE only saves about 10 minutes over a direct RE, which is also pretty comfortable.

(I travelled from Duesseldorf Hbf to Bielefeld myself on RE trains last week.)

MUC not being connected to an ICE station I would disagree with starting the train in MUC. As for 1st class on RE it has values if the train is crowded. First class is usually quieter. If the OP is coming from a TATL he might appreciate being able to seat.

Just to avoid confusion: The regional train RE 6 is leaving the airport station "Düsseldorf Flughafen" at 13:02 and arriving at Bielefeld at 14:58.
Do not go to the old station inside the terminal called "Düsseldorf Flughafen Terminal" which is only served by suburban trains (S-Bahn)!

And: You may use the 9 Euro ticket for this relation, but then it is 2nd class for you (which, since it is a fairly new RRX trainset, has decent seating). Please be reminded, that it is not possible to buy an upgrade for the 1st class while using the 9 Euro ticket!
A 1st class ticket will be about 60 Euros. And if you want to use an IC / ICE train, you must buy a ticket anyway.

All tickets must be bought before boarding the train, there are multiple ticket machines at the airport station.

Thanks!

We just did this in early June. As noted, the luggage was the delay. The rest was simple. Good signage to the skytrain, then an easy walk to the train station (note the RE train was running way behind schedule at the time). Download the DB app and/or the KVB app for train info.
(And IIRC, the 9 euro monthly ticket covered the skytrain, not that anyone checked).

Thanks so much!