DS is 7 (AS) I left potty training until he was three because he wasn't ready. when I did start him day and night he got it straight away and didn't have any accidents. However within a couple of months he would bed wet occasionally.
He is now 7 going on 8 and still bedwetting, I don't make a big deal out of it and so it doesn't bother him. He can go for weeks without wetting and then might wet every night for a week. Basically there is no pattern to it.
Is it worth going to the docs for the spray? as he isn't wetting all the time and it isn't bothering him.