At his age, your feeding regimen may or may not be enough, depending on the day. He will likely actually go through a weight loss phase sometime very soon and this is normal. He will have days where he doesn't really want to eat and days where he will gladly take 60cc. I would go into each feeding prepared to give him 50cc of food, but only actually give him what he will easily take without a lot of sweet talk. If he was a fat baby, he will likely need to loose some weight for his first flight. If he was a skinny baby, he might not. Just depends on how he was raised early on. Don't try to make him lose weight or gain weight. Just monitor it so he doesn't drop too much, too fast or for no good reason. Be ready to be flexible. Just because he refuses a meal today, doesn't mean he's ready to wean or for you to stop offering that feeding.
I tend to start out moving babies to small travel cages where the floor is only about 6 inches below the perch. These cages are around 20 wide, by 24 inches tall, by 30 long. Or something similar. I put food in several locations in the cage so they almost can't get away from it. I really only move them to a bigger cage once they are flying very competently and have been for a few weeks. In fact, most of the time, I don't move them to a bigger cage until they have weaned. I usually move them to their first small cage when they start crawling out of their tub or generally being difficult to keep contained without a cage.
I strongly recommend letting him keep his flight feathers until after weaning if you can possibly do it safely. Keep doors closed, windows covered, toilet seats down. He will be crazy incompetent at flying, but weaning doesn't really start until after the first flight. If they aren't allowed to fly, it throws off their weaning schedule and makes everything harder.
If you have any desire for him to wear a harness as an adult so you can take him outdoors, I'd start getting him used to that NOW. And don't ever slack off on having him wear it. Even if you have no intention of taking him outdoors during the winter, it's still good to put the harness on weekly. Amazons are not knows for being super tolerant of manhandling, and if he isn't used to getting a harness on before he gets old enough to have an opinion, it will be very difficult to get him to wear one later.
Introduce him to all kinds of food that you plan on having him eat later. Sweet potato should not be an every other day thing at this point. It should be every day. Fresh and cooked veggies should be every day, several times a day. Take out the old veggies every few hours and replace with fresh. This will keep him interested. Even though, right now he might not be actually ingesting much, he needs to get used to tasting food and manipulating it with his beak. He will waste almost all of it at this point, but it's important that he have this time to explore so that he knows it's food later when he starts needing to eat because he is hungry. I freshen up the soft food after every hand-feeding when I put them back in the cage.
Get him used to being held by multiple people, seeing dogs, cats, vacuum cleaner. All the scary things that he has to be used to later, let him see those things now. Make sure to wear blaze orange, bright red, jet black. All the scary colors so it's no big deal later. If you are female, paint your finger nails different colors even if you don't normally do that. Where hats, glasses, where your hair in different styles. Walk him around to see the different rooms of the house. Short car rides (in a travel cage that is secured) to places that don't have other birds so he gets used to cars.
Lastly, be careful with that heat lamp. He might not even need it at this point if he is fully feathered. Especially if you keep your house in the mid 70's. Once he starts flying, flapping, or trying to get out, that lamp will be a safety and fire hazard and will probably be warmer than he needs anyway. Also, be super careful about dogs or cats at this stage. I used to keep my cat contained when I had babies in open tubs. Its not uncommon to wake up one day and find the baby out of the tub or standing on the rim, flapping like crazy.