That's one thing you have to decide.... to intervene or not.... my incubator comes back to temp and humidity fast enough that I don't worry about doing a quick candle check when needed and/or pull unruly chicks.. a quick check , especially if there are no external pips poses minimal risk imho.....at this point I would shine a light through the window at the n angle across the shell sometimes they pip externally but it is very difficult to see.... I almost missed one tonight. Till I caught the shadow in the light