You do realise that home-schooling is going to require an increase in effort? If he is ADHD, then there's even more reason to set limits for him and help him to function within them, not to let him just do as he pleases.
Yes, a good and relevant point.
If I might venture a different view though, I personally don't think that "bribing" your child by promising game time in exchange for positive actions will help at all. My parents didn't give me anything for getting good marks at school, or joining sports teams, or cleaning my room or behaving well. I went out and did those things because I enjoyed them, or if I didn't enjoy them at least because I knew they would benefit me in the long run. If there has to be a bribe to do anything, then that screws around with the motivation.