I've learned that going potty is more about independence than about bladder and bowel control. Start teaching him to pull his pants up and down on his own, let him undress himself at bathtime, etc. Give him every opportunity to practice. You might want to put him in pull-ups and he can practice pulling them off and on at diaper changing time. Once he's pretty good at dressing/undressing himself (this could take a month or two), introduce the potty. We usually introduce the potty by having them sit on it before getting in the bathtub. We did it that way with our daughter, and we have also done it with our son (22 mo). He regularly pees in the potty before and after his bath. He's not quite 2, so I expect we'll be in a holding pattern at this stage for a couple months. From our experience with our daughter, and from what countless friends tell me, all this potty stuff really clicks when kids are 2 1/2. Literally, almost to the day, friends tell me the dressing/undressing, much fewer accidents, etc. all come together at 2 1/2.
When it's time for underwear (he's good at dressing and undressing, and he is comfortable using the potty), I'd clear a couple days on your calendar (my sister-in-law took a 4-day weekend) to stay home all day, stock up on juice boxes or kool-aid or whatever he likes to drink, and put him in underwear. You'll have a couple days with a LOT of accidents. After that, he should start getting the idea. In the beginning he'll still need a diaper or pull-up for naps and bedtime, but don't use them any other time. When you go underwear, you use them all the time - even if you're running errands. Just take a couple changes of clothes with you everywhere and make it a habit to take him potty before you get in the car and as soon as you arrive at your destination (welcome to the joy of a toddler in a public restroom).
And, of course, remember to always be positive and don't get into the control battles. Accidents happen. You should try to handle them with empathy rather than anger -- say things like "Oh! I see you've had an accident." or "Looks like you didn't make it to the potty in time." and "Don't worry, we have dry clothes for you." "Let's work on making to the potty on time next time, would it help if I set a timer to remind you?" etc. Just make sure you have a good carpet and upholstery cleaner on hand, and reward yourself (and your house) with professional carpet and upholstery cleaning when potty training is over.
And don't fret if you have a "false start" -- he won't be scarred for life if you start potty training and it's not quite the right time.
Good luck!