Potty training

I had high hopes that I could potty train spencer this fall. I even bought him a potty chair and underwear for his 2nd birthday. He used to tell me when to change his diaper. I think I missed my window of opportunity. I'm not forcing him now but with the oldest two I did force them to learn so they didn't go to sunbeams in diapers. I think when you wait longer, they get more stubborn and they are lazy. I can't get him to even sit on his potty with his clothes on. Too scary, he says. This is one parenting job I want to pass off to dad or aunt Tonya!  I was hoping to save money on diapers but alas, we shall wait... Until who knows when. I'm not sure what to wait for. A first step would be not screaming if I try to get him to sit on the potty.