Help with potty training


I need some advice on potty training my son. He will be 3 in January and I'm really wanting to have him potty trained by end of October because that's when our second little boy is due! I bought him a seat to go on the toilet, a stool, and he will get 3 gummy bears for every time he goes. I also have a little kitchen timer that I set for 20 minutes, once it goes off, we try to potty. He is in Huggies pull-ups now so no more diapers. When I sit him on his seat, and say "time to try to potty!" He keeps saying "no momma, no momma" I'm at wits end. 30 weeks pregnant and my patience are thin already, I just can't get him excited for it. And he doesn't like running around naked outside, so that option isn't really gonna help. Cheerios in the toilet will be for when he gets a little bigger, even with a stool, I don't think he'll have an easy time peeing and standing up, but I could be wrong.