Certified GKH Gardening Expert
I don't, normally, use a dome unless it is unusually dry in the area. Typically, if you do use one, you will remove it shortly after they sprout. The problem with this is that you will need to acclimate them slowly. Since they are started under such specific conditions, any quick change will likely kill them.
For the first few days, leave the dome so that air can get inside. If it has vents, then open them. If not, then set the top, crooked, so that the corners get air. After a few days, you should be able to take it off.
When starting without a dome, only the strongest seeds will survive, leaving you with a more hardy crop of plants. This will require careful monitoring of soil moisture, though.
This collection of articles will give you more information on seeds, and starting them: