I've had my group of 8 (3M, 5F) for 3 days. One female was already berried and then last night the largest girl molted. This morning I woke up to that same female berried.
Look for the yellow/green saddle on the females. I hear that once the saddles becomes pretty noticeable you will have eggs shortly after. If you see no saddles then you might have a bunch of males or immature females.