You all were such a help to me getting a handle of this potty training issue we've had going on, so I thought I'd update you.
Hayden has improved immensely over the past few weeks! We went back to pull-ups and stopped talking about anything potty related. I would only ask him occasionally if his pull up was wet and tell him to change it if it was. It didn't take long for him to start telling me he needed to go, which would earn him a reward (a marble in a cup...once full, he gets an ice cream). The only time I really said anything about the potty was when I saw him hiding to go poop. I'd just simply say, "Go to the potty if you need to poop." If he did, great, if not, no big deal. Anyway, in the last week or so he has only had a few accidents. Everytime he goes it's because he tells me he needs to (except bedtime-that's part of his routine). The really exciting part is that he has announced that he needs to go poop about 4 days in a row and gone without hiding or being told to go! We have been over the moon about this turn of events! Unfortunately, the past two days he has pooped in his pull-up, but DH and I are so much more relaxed and non-chalant about it when he has an accident now. I feel so much better emotionally about the whole thing. I'm not stressing about it in the least even with this baby coming in 9 days. About a month ago I was worried that he may have to wait a year to go to Kindergarten because of his progress with PTing (I am SUCH a worrier) and now I can see a big light at the end of the tunnel! DH is pushing to put him back in underwear, but I'm perfectly happy with where we are now and don't want to push it too soon. I want to give him a chance to get used to the baby being around and leave the stress off me a while longer.
Thanks for all the advice and support!