Toilet training

Hi there
I am hoping the wonderful experts on here might have some ideas to help us!
Our wee boy is 2 and a half and is showing all the usual signs of being ready to be toilet trained. Im a big believer in not pushing children into it before they are ready. But all of his own accord for the past month or more he has been taking his nappy off and sitting himself on the potty or asking me to put him on toilet. He sits there sometimes for quite awhile but then asks for a nappy. I put it on him, he wees in it, then takes it off and tells me its dirty and yucky. If I leave him with his nappy off he can hold on for a couple of hours so doesnt really have accidents. I get the impression he really wants to do it but is almost scared to let it go if you know what I mean?

Anyone had this before or have any suggestions?
thanks heaps

We haven't had this problem, but started potty training by letting our boy run around outside with no pants on and talking about "doing a wee" when he did one.  Then we encouraged him to go out on the deck to do a wee (had to put up with several accidents on the carpet until he got the hang of it).  He would then get a container of water from the paddling pool and pour it over his wee to clean up - good boy eh?   After a couple of weeks he just started using the potty inside of his own accord, for both 1s and 2s - although he sometimes prefers to pee on the deck .  I think that being allowed to pee outside and watch it and talk about it helped him learn about letting go without having a nappy on.  Now we just need to teach him about getting dressed and undressed - he has no clue or desire to do that himself yet, and will just wet his undies/pants if he's wearing them but no nappy .

Sorry, that was a long winded suggestion!