Kakashi said, that Sasuke can't handle the technique yet. And it took him a little while longer - he was late at the 3rd round.
Well doesnt matter - this has nothing to do with the true story anyway.
It's also stupid, that Gai knew that Kakashi was training Sasuke, but when he saw Sasuke using Chidori against Gaara, Gai was rather suprised...![]()