A.W.
NO i do not think that you should go back and explain it if he ready that just help him along the way and reward him for good job when he goes. let him go bare bottom when you are home and it is just you, him, and daddy try and help go and you and daddy take him to the potty when you guys go. If you feel like you don't want him to in bare try under ware but ONLY at home. When you go to the store tell him look here are some Big Boy undies and maybe give him a 2 kinds to choose from. He WILL have accidents and there maybe more than 2 or 3 of them but just let him know that he is a big boy and it's ok to have an accident. but do reward him when goes in the potty. I did both of the ideas that i gave you with my oldest and she got the hang of it but don't remember how may times we had accidents and how many times that i had forgoten that she had pantties on until it was to late and we have to buy new clothes b/c we we out. BUt don't push him into going just take him when you go and let him just set there. hope that the advice helps you i know that training boys and girls are diffrent but may i helped a little
GOOD LUCK