A FlyerTalk Posting Legend
Join Date: Sep 2009
Location: Minneapolis: DL DM charter 2.3MM
Programs: A3*Gold, SPG Plat, HyattDiamond, MarriottPP, LHW exAccess, ICI, Raffles Amb, NW PE MM, TWA Gold MM
Posts: 100,404
It would not be wise to arrive at the gate 15-20 minutes before departure, especially if the flight is full, as is likely for your travel times.
As FO, you board in zone 2 (unless upgraded, which is unlikely for this route and times), which is important for overhead bin space. Boarding should begin 30-40 minutes before departure time. You should plan to be at the gate very soon after boadring begins, at the latest. If you are not there by T-15, you risk losing your seat without compensation.