Nice to meet you Charlie and Karen! Your chicks will be fully feathered when all the fluffy down is gone from their chest, head and neck, but they can probably go outside any time, depending on how well they're acclimated and if you can still provide a heat source for a bit longer. They only look to be around 2 and 3ish weeks old. My chicks have usually been feathered and off heat by 5 weeks, but I move them to the coop at 2 weeks with a Mama Heating Pad.
Welcome! It's never too late, I'm 50 and have been repeatedly told it's not too late. (Although I *am* grateful to have @Purple Rose , my energetic teenager and animal whisperer, to do this with me!)
You have a beautiful little flock! I hope they bring you much joy.