It's good he's trying to be proactive about it, what are the chances he resumes playing next season after just having heart surgery. Seems like something he should really take it easy with honestly.
If he has the nonsurgical ablation, he should be back to full strength within a couple of weeks (more like days, but he'll probably have activity restrictions that will keep him out of the gym for a couple of weeks). Even if he opts for surgical ablation, there are varying degrees of severity and he would be back to normal well before training camp opens barring complications.