Leggy cabbage

I've got a tray of 9 igloo cabbage seedlings which are very leggy. They germinated quickly on my shelf in the conservatory. I'm going to pot them on up to the first leaves in fresh compost. Where should I put them after? They must of got too much light and warmth where they were.

 

They probably did have too much heat, but not enough light.
I'd pot them up to the first leaves like you say, but then put them in a unheated very light place..coldframe /greenhouse or under a make shift clear plastic sheet. Cabbages are relatively hardy, but they do like full light.