When should I start introducing a sippie cup to my son?

You don't have to force it on him. Just offer it, if he takes it great, if not he will eventually. We started my son on a sippy at about 6 months when he had his solids and he takes it sometimes and sometimes he just tosses it around and makes a mess with it LOL which is totally fine. Don't force anything on him but I'd definitely try if he's not taking his bottle. Good luck hon :)