Toilet Training! HELP!!

My son is 2 ½ years old and I am planning to start toilet training. The only problem is that he is not so good with communication as he hasn't started to speak much and communicates with us through actions. I know when he poops as he sits in a position and I know I should rush him to the toilet that time but I am worried about the peeing because he tends to drink a lot of water. I am actually very much worried regarding his toilet training but I am also hoping he gets the hang of it by the 3rd week. Still confused which method to use. Should I keep him naked or should I make him wear underwear?

Please suggest or share your opinion.