Being physically ready and being ready mentally are two different things.
We didn't get our son really potty trained until just about now, age 3 1/2, even though he could use the potty by age 2. We had him in a soccer camp a few months ago... and for the month before it started, we told him there's no diapers allowed at soccer camp.... We told him he had to practice on the potty, because he could only go to soccer camp in underwear. This worked wonders on his progress. We still had lots of accidents after that, but still a lot of progress.
I think it is all about control...when our son decided that the potty would be an agreeable task, he's been great. Before that, it was war... with screaming fits about using the potty..... oh, such a big waste of our time.
In my opinion, you need an incentive that works for him. Soccer camp was the turning point for my son!!.
You should find out what the pre-k is doing for potty training. Even if you send him in a pull-up, they should still be taking him to the potty.
The "newness" concept is very true. It wore off in our case too..... but hang in there.. our son sort-of regressed once or twice in our year-long process to get him 100%.
Even now, he tries to hold it when he's engrossed in some toy ... we see him get all fidgety.. and then we chase him off to the bathroom before he has an accident.
I don't think you are as far off as you think..... if other kids in pre-school use the potty, he will want to do it too ... practice practice practice. (and lots of good luck. )
(by comparison, I have 2 yr old boy/girl twins too. The boy won't even sit on the potty without screaming in protest, yet his twin sister is totally mentally ready. She rips off her diaper and sits on the potty, but nothing comes out. Then she wipes and flushes and fights to only wear underwear.
i think that is the perfect example of boys vs. girls. Theyeven have their big brother as a guide, but still they behave completely different on the subject.)