M.
If you can promise your son (and yourself) that you will remain relaxed, if you can look at it as a several-month process (improving as you go along, though it could be shorter than this, set your expectations for several months), and if you can approach this as a team effort where you communicate with and help him to be successful at using the potty, with NO negativity or shaming or visible frustration, then it's the perfect time to start NOW.
For your child, there is no advantage to waiting - the longer he's in diapers, the more he gets used to that being "the place to potty" and often, the more difficult the transition the longer you wait:
http://www.azcentral.com/families/articles/0726pottytrain...
If anyone tries to scare you out of starting now or promises you that it will be easier if you wait, just keep in mind that over half of the people on this planet are potty trained by 12-18 months with no negative physical or emotional side effects (caregivers expect accidents, learning process, remain relaxed, no shaming or negativity). And keep in mind that since the age of potty training has risen dramatically here in the USA over the last 100 years to ages 3, 4, or 5, kids are experiencing more bowel and bladder issues than ever before (constipation, withholding stool, bladder infections, incontinence).
To help you keep perspective, remember how you supported your son in learning to crawl & walk (and he fell, a lot, and that was how he learned, and there was no shame) or gradually introducing solids (first mushy, then lumpy, then small bites to chew, etc.)? If you approach potty training in this manner, you and your son will have a successful, enjoyable time potty training.
Your first task is to be really open with him about pottying - always go to the bathroom together, take him along with you, have him sit on a little plastic kiddy potty while you sit on the toilet, tell him what it feels like to have to go to the bathroom (so he can start to associate the sensations of having to go with the result of pee/poop coming out). And I highly, highly recommend either letting him go naked whenever possible (even if that means you guys decide to play in a confined area for an hour or so). If naked isn't feasible, then I suggest using plain, cotton training pants with no cover whenever you possibly can. The opportunity to be naked or wear simple cotton underpants really gives them immediate feedback to help them connect the feeling of "having to go" with what comes next (wetness, etc.) and it really speeds up their comprehension of how their bodies work. If they're in diapers or cloth w/ a cover, they don't get the same sensations and it takes them longer to connect the feeling with the result.
And there will be accidents - this is how we learn! Expect that there will be accidents, embrace them as a crucial part of the learning process! And together, matter of factly (not punitively or negatively), you guys clean it up as a team ("wow, you really had to pee, look at that big puddle! next time you're dancing around like that, tell me, and we'll try to use the potty together. I have 2 paper towels here, one for you and one for me, let's clean this up and then get you in some dry, comfortable underpants").
Bottom line: if you're ready to help your son with potty training and you have a gentle, loving approach and realistic, gradual expectations, your son will respond well to the transition from diapers to the potty. I can't emphasize enough that potty training as a *process* that's not a drive-by, "done in a weekend" thing (potty training in 2 days is the exception, not the rule).
For more information on the different ages of readiness and practical potty training approaches:
http://www.naturalfamilyonline.com/5-diap/46-infant-potty...
Hope this helps. Happy pottying! :)