I totally forgot to respond to this a while ago. I usually don't move babies into a cage until their first flight. I know plenty of people move them to a cage sooner but I usually make it a gradual change. Once they start flying they spend the day in the cage and the first couple of nights in the brooder. I also make sure about half of the cage is covered with a towel to prevent drafts and give them a place to hide. I usually start introducing real food by sprinkling some parakeet or cockatiel sized pellets and sprouted seeds around the bottom of the brooder. They crumble it up and carry it around without really eating it for a couple weeks or more. A few days or a week after they start flying, you'll notice that they actually start ingesting their adult food more often. Expect them to be hit and miss about taking formula during this time. They go through a weight loss stage prior to flying where they just let formula dribble in a river down their chest. If they are being difficult to feed and making a huge mess, I usually consider that refusal of formula and put them back in the brooder a little hungry with the sprouts, pellets and some warm soft veggies to pick at. I also do a lot of cooked sweet potato since other things can be ground up and added to it to make a mash. As they start flying, you'll notice on any given day they may refuse a feeding or be desperate for that feeding.
The biggest mistake I made weaning my first batch of quakers was that I was so concerned about their weight because they were a little low to start with that I sweet talked them into taking formula when they really didn't want it. This delayed their normal pre-flight weight loss and decreased their appetite and motivation to eat on their own. It totally messed up their weaning and I ended up having to almost force wean them much later. Pay attention to the baby's signals. If its not that interested in food, don't push it, put it back in the brooder with some adult food to eat and try again in a few hours. If they are being really picky about formula, I usually consider it doing okay to get one or two good meals into them at about that age. The rest of the feedings might just be a cc here and there. Its fairly normal for babies to lose between 8% and 20% of their weight getting ready for their first flight and shortly after. How much they lose depends on how fat they were to start with and how picky they get. If they have over a 10% weight loss, I start taking the time to persuade them to eat a little more formula, or add another feeding even if they are only willing to take a little bit but I don't make myself crazy over it unless there are other symptoms of possible illness. It seems to be a natural process.