The best thing I did was to 'volunteer' to go in a couple of mornings a week while I was still on my maternity leave (I could test what routine would be like, my boss thought I was heroic). I'm so happy that I didn't have to go straight into full time from the day I'm supposed to resume. I had about 10 weeks off for my first, 2 weeks partial mornings and a few full days,then back FT.