Potty training with m&ms

My toddlers been doing so good with pooping in the potty. I give him an m&m if he poops. Now he knows he's going to get one so he asks to potty when he needs to go. He always says yay chocolate!

He's a younger toddler so I'm wondering when should I wean him off the reward? Chocolate isn't something I normally give him or want to give him often but it was suggested by another mom and so far it's worked well. When should I transition and how? I know it will be a few months at least before he's really mastered the potty all together so I'm not sure what to do. I know he'd probably get really upset if I just stopped giving it as a reward. Any ideas for me?