When should I remove the seeds from the propagator when germinating?

Hello, I started germinating 10 seeds 2 days ago in a homemade propagator. The seeds were placed in peat moss. 1 of them sprouted and I can see the other ones starting to come out. Now my question is, should I remove the plastic cover to give them air? Or will they be fine in there for another couple days? Thanks

leave it be till you see the first set of true leaves and they are developed.