The best bet is to wait until she is ready. That's usually around 2. Then you take her to the potty often until she gets the idea. Then put her in panties and keep a close eye on her until she is old enough to tell you she needs to go or just goes on her own - that's usually before 3.
If you start now, just take her to the potty every half hour until she gets it. Do not force her to sit on the potty. As she gets older, she will learn to tell you she needs to go or will just go on her own - that's usually before 3.
No matter which you choose, she will be fully trained at about the same age. So - starting now means you will have lots more work but possibly fewer diapers, you can also "brag" that you are potty training now. Starting when she is ready means lots less work, probably more diapers, and you get to tell nosy relatives to back off.
at 10:40 PM on Jan. 14, 2009