I would definitely wait at least a week after surgery to start smoking again. You want your body and immune system to be in the best possible position to effectively receive the grafts and the smoke/nicotine is not gonna do you any favors. The first 5 days or so after surgery are crucial, so don't do anything to jeopardize that. Heck, I would even consider the HT as a launching pad into stopping smoking altogether. In addition to all the other health risks, smoking has been also been linked to hair loss, so it almost seems counterproductive to keep it up.