I just did it and near as I can tell ( I asked here) they are about 3-4 weeks. The girls are using it already. I took a small limb about 1" in diameter and they seem to be fine with it. Picture shows it in the back of the cage.
Quote:
I added a little roost ( you can just see it in the above pic) on the floor when they were young like you say and they started using that one right away.