4-5 week chicks

I have these two chicks that are about a week older than my other chicks, they have most of their feathers now except for a little bit on their backs, I was wondering if it's too soon to put them in the coop starting next week? weather shows during the day it's going to be about 60 to 65 but the lows being at night being anywhere between 40 to 45. these two are the ones that I think are ready. I think the other ones are still a little too small. should I wait till the smaller ones are ready too?