buy one now and make it available after baths.
pt-ing was uneventful and mostly done by 2 y.o. (even w/ bringing a new baby home) because we kept it available and didn't make it a big deal. Except when she actually used the potty, then we went crazy with praise. People on the 24 months plus are a little too late for this advice, so thought I'd share what worked for us and what friends have said was the most helpful for them too!
Re: the secret to potty training...
I totally agree with this and did the same thing with DS. Only we got ours when he was about 18 months and he started wanting to use it a couple months later.
He's in underwear when he's awake for us too. I'm not very concerned about night training at this point since he always wakes up soaked.