It would be a few month when you had a few dozen computers with very powerful GPU boards as graphics cards. For orthodox chess.
But I should point out there is another approach called NNUE, which uses a far simpler neural net just for evaluation in a conventional alpha-beta search. This is far easier to train; for orthodox chess a few hundred-thousand positions from games with known outcome would be enough.
It would be a few month when you had a few dozen computers with very powerful GPU boards as graphics cards. For orthodox chess.
But I should point out there is another approach called NNUE, which uses a far simpler neural net just for evaluation in a conventional alpha-beta search. This is far easier to train; for orthodox chess a few hundred-thousand positions from games with known outcome would be enough.