2022 - What I sowed today

I'm carp at getting lettuce to germinate, and when I do it's far too many. So I've sowed some in pots and put them in the fridge, is that the right thing to do? How long, if at all, do they have to stay there?  Bren, come to my rescue.

I just put them in the fridge overnight. It doesn't need any longer to trigger them into growth.