Not usually longer than 9 months hun! Sorry, I shouldn't be flippant, I know how hard those last weeks are. But really, there is no way to know. I had no pre-labour at all with DS1, with DS2 I had weeks of it (but it did start a lot earlier than yours).

I really hope it happens soon for you hun. The best things to do are to stay active and relaxed (ie try and forget that you have a baby due any day, as hard as that is!).