When to take Cover off germinated seeds?

[Germinator]

I was taught to take the cover (plastic wrap in this case) off the seed tray when the first tomato seed sprouts. But, I believe in Craig LeH.'s video, he said to put the cover back on until all seeds have germinated. The plastic wrap is hitting the top of the little seedlings now. Does anyone have the definitive answer on this? In the past, I have removed the cover after the first germinated seed comes up. I have a 1020 tray with 48 cells and about l/4 have germinated in 5 days. Greenhouse temp. is 63 but flat is holding around 85 degrees.