If he's around 10 weeks he will definitely be looking for food to eat on his own, while still needing the formula. My breeder had suns, some of which had weaned themselves by that age, some that still needed a feed or two. I would be doing what Pedro said, pellets, a little seed even, veggies, soft foods etc. Have them where he can get to them 24/7. Really soon as the bird is out of the hot box/brooder and into a cage they should have water and food, even if they are not eating or drinking on their own yet just to familiarise them with it. Alex would play with his pellet and seed mix looooong before he ever had the slightest inclination to eat it. Same with the water, fruit and veg, etc. So when the time came for him to start eating, he was already familiar with the food.
Alex took FOREVER to wean though, because just as he was weaning his breeder fell ill and I had to take over hand feeding him. He was too stressed to wean with he new environment and new handler. It took a month of building a bond before he even started to eat on his own. He's nearly 6 month now, and it's only been the last month that he's been off the formula.