Hi Cindy,
I have a son who is 25 months and for at least 6-8 months we've had a potty in the bathroom since he showed a lot of interest in what we were doing.
At first we just put it in there and let him check it out. Then we had him sitting on it with his clothes on. Some days he'd sit, and some days he wouldn't. I got a freebie Charmin potty training kit (a little book, stickers, poster, etc.) and we would read that together while I sat and went (or dh) and he sat on his potty.
Then, I added it as part of our bathtime routine. We go upstairs, get him undressed and as I'm letting the water fill in the tub, he sits on the potty and we read books together. We've been doing this for several months, and he's peed five or six times. I know he's not doing it because he knows that's what it's for. (At least, I think so.) I think it's just that he has to go, and so he does, regardless of being on the potty.
When he does it, I cheer, and give him lots of kudos and talk to him while he's playing in the tub and I'm pouring it out and cleaning it up. I know he's not ready for pullups or underwear quite yet because we haven't gotten to the point where he is uncomfortable with a wet or dirty diaper.
I've heard a lot of parents say that kids are ready when they start asking to be changed, they're ready, and it sounds like Xander is doing that. What do you do when he asks to be changed? I've heard some people say that you should take the dirty diaper (I don't know what to do for pee!) and drop the poop in their potty (or your toilet) to show the child where they should be going.
I definitely wouldn't rush the underwear thing. You've got a long way to go and a lot of accidents a long that way. He's probably already feeling the pressure of using the potty. He doesn't need the added pressure of not messing himself, too.
Every child will use the potty at a different age. Some kids do it early, and some kids take a few extra years. I know a lot of parents worry about it, but it's not something to worry about. After all, when he's 18, no one is going to care when he got toilet trained, they'll just be happy that he is then!
I'd love for more "seasoned" parents to stop by for some potty advice. I know I'm feeling the pressure of not doing enough to help my son learn, and so I'd love to hear more stories.
Oh - one of the books I have to read on the potty is The Potty Book for Boys by Alyssa Capucilli. IT was the best one I found that didn't sound too silly.