Expect them to either leave on their own or to be thrown out by the hen at around four to five weeks. They normally stay in the cage with the male and he makes sure they are eating. Once you see them eat on their own, be sure to remove them immediately. If they try to return to the nest, the mother bird may injure them as she is probably in the process of starting a new clutch at that time. Keep all the babies in a cage by themselves until you are completely sure they are eating well and then you can put them in your general cage.
They start by peeking out and then venturing out a little and going back in. For a week or so, they still like to sleep in the box and go back in from time to time.
Yep, my Freckles spent about a week peeking out, then fledged at 31 days. The past few days he's been spending his time partly in the cage and partly inside the nestbox (with his two younger siblings).