I would play it by ear. It could go either way - you are well and will be bored at home if you finish up too soon, or you could be tired and not well and really struggle, especially with such a demanding job. I would try to keep your options open.

As an interesting aside, my Mum used to be a school teacher and in those days you had to resign as soon as you were pg. Mum worked until 4 months as she was organising the school musical and wanted to see it through. She said if they realised she was pg and were concerned about it, let them be brave enough to ask her! They didn't, good on you Mum!