Bear in mind that his first flights are going to be awful and potentially quite scary to watch.
Think about a child learning to walk. They only have to move their legs on a surface and they still fall all the time. Flight is far, far more complex: in order to fly, a bird must master taking off and landing, steering, turning, and controlling their height and speed among other things. They can move each feather independently as a flight surface: the interaction of flight surfaces with the air to produce thrust and lift is what allows them to control their flight. Your bird wiil get it wrong. He will crash land, he'll sometimes zoom around the room and not figure out where to land, he'll sometimes fly somewhere high and not be able to get down.
However, again, think of a child learning to walk. Yes, those falls can be distressing to experience (for the child) and witness (for the adults). The answer is not to scoop them up and hobble them or place them in a wheelchair. Instead, we let them fall and learn. Over ttime they acquire more control over their limbs, and in no time at all they're running and dancing and playing.
My advice is to have his first flights in a small room so he cannot get up enough speed. As
@flyzipper says, make sure the room is bird-safe - cover mirrors, make sure that the windows are closed and curtains or blinds are drawn, and make sure that there are places for him to perch e.g. playstands to fly between.