How long do I wait for him to ask?

It sounds like he has a problem with committment. The fact that his ex left when his little boy was only one and left the little boy behind as well is not good. You need to ask him if you havent already why he has this committment phobia, maybe his ex obviouly wasnt the right person or maybe it has something to do with his childhood. Either way you have to know and ask him how much he loves you. If he is happy that his little boy calls you mummy then that is a good thing, he might just not need a licence or wedding ring to prove his love for you. You have to ask yourself how much you really love this man and is the fact that he might never want a wedding enough reason for you to walk away, after all a piece of paper and a ring dont make a relationship work, its the two people in it that does. All The Best.