You'll have to wait until your puppy's shots are completely finished. That's usually around 16 weeks, I believe.
In my opinion, the earlier the better. That way, they get used to it while they're young. A lot of people here do it themselves, and a lot of people get theirs done professionally. It's just a matter of preference. I know I would do a horrible job, so we take Franklin in to get his done professionally.
Here's a link to a video tutorial Marcerella02 did... they're really good!
http://www.yorkietalk.com/forums/sho...d.php?t=117723