my ds was exactly the same he used to go for a nap around 1pm and i would have to wake him at 4pm it was lovely, however he went to bed at 7.30pm every night but not actually go to sleep until around 11pm finally christmas eve that was it, after i did the santa thing i went into check on him and he was sitting up reading a book to his teddy, it was around midnight - he never came out but was always a bit tired in the morning, so it became a bit of a vicious cycle he was coming up to 4yrs of age and i stopped his naps, instead i just encouraged quiet time on the couch watching a video just after lunch - some days he slept and some days he didn't. even now at 6yrs of age he gets really tired after school and likes to "chill out" for a while, when he was at kinder quite often he would come home and fall asleep.

it is nice when they sleep like that and you get your golden time you wish sometimes it didn't have to end lol.