Posted: 10/03/2014 at 13:30
I tend to remove the lid to my propagator when I can see the majority of seeds have germinated. It provides more light and (in my mind at least) reduces the chances of any fungal diseases. Get them on a bright window sill as soon as possible and rotate the trays each day so they grow nice and straight.
I've had my tomatoes in the greenhouse (unheated) for about 3 weeks now. I brought them in overnight for the first week to gently acclimatise them. Now they are strong little plants.
I think provided you avoid any extremes of temperature for the first week or two when you put them out they will be fine. Oh, and remember to water them in the morning if there is a hot day forecast, I only just got to mine in time last weekend as they were starting to keel over!