Congrats on the new baby, he is definitely over a month, they normally fledge at around 6-7 weeks old so my bet would be around 2months old.
quakers are fantastic little birds, make sure he is on a good diet with pellets and plenty of fresh foods, sprouts etc... Not too much seed, or if he is eating the pellets a fresh foods well you can cut it out altogether or just offer as a treat.