potty training

ok,as you all know vince is now 2 years old..i have mentioned before that i want him in preschool both at age 3 and 4..i want him to have the social skills and i want to see how his health is before school "matters" now i know of atleast 1 school that i can get him into and he would not need to be potty trained..but this is a private school which could get costly! if i put him in the public preschool he qualifies based off medical needs for free schooling..but would need trained..he knows how to take his "diapy" off,take his pants off,sign potty,wants changed when pees or poops..soo...how do i go about it..i know 1st thin in the AM..but then what..every 1/2 hour? after he eats? do i give him a book to try and occupy him so the time goes faster? what about when we are not home? he is starting therapy twice a week 30 minutes from home and is afraid of the "big potty"...i have heard plenty of times that boys take longer than girls...but i feel i should atleast be TRYING! please give me all the info you have :)

small update***

ok,so after vince not eating the past few days and puking or atleast gagging when we give his enzymes,so i called the dietician and we talked alot! she says to take him to the peds for a possible ear infection or sore throat...she also still recomends behavior therapy (but finally admitted,the therapist would be counseling us,not vince) we have tried everything and i am not gonna go to a counselor on how to feed/raise my baby who has been nearly perfect his entire life! the dietician is happy that i am putting vince in a toddler group food clinic where they address both sensory,behavioral,health and medical needs all involved in each child...its a 30 minute-1 way drive..so 60 minutes 3x a weeek..but help me grow has agreed to pay the gas money! vince ate sweet potatoes once really well...and then dinner was his once favorite yogurt..he fought at 1st,then i gave him his prize bowl (with his rewards and treats) and he took 2 bites with any fight...then gagged once and puked TONS!!!!!!!!! dietician also mentioned a blockage which i didnt believe until tonight when he had sweet potatoes again and began gagging towards the end...hes still pooping a good amount (although hadnt gone all day saturday) so depending on how he does food and poop wise tomorrow will determine either a ped visit or an ER visit...
and another thing..his toes used to crack on the bottoms in the winter with footie pjs..well we got his toes healed up by leaving his feet bare as much as possible..then we started putting footie pjs on again with the AC on (as he loves it) and his toes are bad! his right big toe looks like it was sliced open with a knife on the bottom! its not actually bleeding,but you can see the red open sore and its the whole crease where the toe bends under...we showered him and then put some A and D on it with a band aid (and tape to make it harder for him to get off) hoping it starts helping..but i think i want his toes tested for bacteria!