Okay, I am actually against fully free-feeding in dishes.
In the wild, birds spend a great portion of the day foraging (scavenging) for food, yes? This keeps them mentally and physically stimulated throughout the day. In captivity, birds are often offered a bowl filled with food right in front of them and absolutely no work is required to eat, essentially giving them too much time on their hands that often results in boredom.
Enrichment is VERY important in parrot ownership, and it's not only about chewable wood (which you do need to make sure is available in the cage at all times anyway). Working for food will keep your parrot entertained during the day, and he also gets the satisfaction of eating what he found.
In the first few days, I would leave a food dish available at all times just to get your bird accustomed to his environment, and also to make sure he is eating.
Over time...
- I would set up several small dishes/ foraging cups(found online or at a store) everywhere, each containing only a small portion of food. This way, your bird will have to climb around to find his food.
-Skewer veggie chunks through cage bars and also on a skewer. Place these around the cage.
-Wrap bits of nuts and seed in tissue paper, tie it against cage bars.
-Buy foraging puzzle devices either online or at a store, preferably online
The above are just a few ideas that are super easy and I'm sure you can come up with more.

Remember, parrots are very intelligent creatures that NEED to be stimulated!