Just a word of advice - not because I care so much about you, but more because the fewer accidents riders have ... the less 'heat' (pressure) there is on our sport:
When learning, one often (always) tends to think one is better/more fluid/more accomplished than one really is, yet riding skilfully, smoothly and quickly is an incredibly complex task (skill set) that builds with time and experience. When riding in a group, there inevitably is group pressure, group dynamics and one's competetive nature that 'kicks in'. And usually, there is always at least one rider that is faster than you or I ...
Generally, riders tend to follow the rider in front of them, judging (trusting) that rider's lead-in speed in corners. The thing is, though, that that rider just might know that corner a bit better, or have much more experience than do you ... and what so often happens is that a newer rider finds themself 'going in too hot' ... gets scared, the adrenalin things explodes and then the rider panics - and then everything goes to shit (and that drop-over point might be only three or four percent above your own comfort zone/skill set, yet still 20 percent within the leading rider's personal safety zone).
Do NOT follow the rider in front of you, speed-wise, unless you know that they know your skill level imtimately, and is adjusting their speed accordingly. Once you are actually setting up and in a corner situation ... it is too late to bleed off speed ... unless you are highly skilled at trail (late) braking - which you won't be.
Also - do NOT watch the rider in front of you ... as you need to be LOOKING AT THE ROADWAY UNFOLDING IN FRONT OF YOU and your coming line/direction of travel ... or you will likely crash.
So, when someone says "ride at your own pace" ... THAT is exactly what that advice means ... and it can save either your bones and your life ... or at least a lot of money repairing your beautiful new 250/500/650/750.
Good luck on your first group rides, and safe riding ...