Sticking with pace group during marathon

Hi everyone! I’m running my first marathon in just under two weeks (Sydney marathon!) and was wondering about experiences with pacing/pace groups.

I have a goal finish time in mind, though not super strict. What are people’s thoughts/preferences on sticking close to a pace group throughout the race? I don’t think my mile splits will be super consistent, so was unsure if trying to stay at my goal pace the whole time or at least in the beginning will mess me up. Any opinions or thoughts are very appreciated :)