Moving Bantams chicks outside and off heat

[HenSolo123]

I have a little flock of 3 & 6 week old d’uccle and silkie chicks. They’ve been on my front porch with a heat plate since two weeks old, with temps dropping to 20-30s here in Kentucky. When did you wean your bantams or small breads off the heat source when nights are still pretty cold? I’m ready to move them to my backyard but don’t want to have to extension cord their heating plate.
Picture of them last week in their setup:

 

[Yardmom]

The 6 week olds are ready to start being weened of as long as they are going to a dry draft free place. The 3 week olds need heat for a bit yet.

 

[HenSolo123]

Here are the big kids today
Born 2/2