Determining Race Pace

I’m running NYC and struggling to figure out what my goal average pace should be. This is my first marathon, so when I started training I had a goal of just finishing, but want to go into the race with a more concrete plan than that to ensure I’m not going out too fast but also not selling myself short.

My long runs have been between 10:11 and 11:02 average pace, mostly hovering around 10:35, and I’ve felt pretty good on them but I’m nervous about losing steam in miles 20-26!

Any advice on how to determine a realistic marathon pace? Thanks!