I teach secondary Englsih and I left at 30 weeks! Don't regret it one bit!

Like Calleigh says you might get a 'burst of energy' by then but it's all relative (like walking to the corner shop). I also think that sounds like a wonderful time of the year to start your ML!
K x
PS I was 8 days over but I really had only just started to get bored - I always had as much planned to do as I could x