I would say thats reasonable, most people ive spoken to have taken their MAT leave around 6 weeks before their baby is due for a few reasons, 1) baby might come early 2) at the stage you will be, your most likely to feel absolutly knackard! and some people will have the opportunity to use their years holiday up before baby is due so their might not be a need to start MAT leave until after baby is born.
My holiday runs Dec to Dec and in a few weeks i will be asked if i want to use it all in one go before baby arrives or if i want to carry on and have it as pay. Financially it might be better for me to take it as pay as the MAT leave i get will be a lot lower than what im earning now. I intend to take a whole year out before returning to work.
Oh but dont forget you can start maternity 11 weeks before babys due date, i was going to do that but soon changed my mind due to finances. Oh what a nice holiday that would have been!
Tiggy xx