It's at 31 weeks actually but some will disagree
First trimester:
Month one: weeks 1-4
Month two: weeks 5-8
Month three: weeks 9-13
Second trimester:
Month four: weeks 14-17
Month five: weeks 18-21
Month six: weeks 22-26
Third trimester:
Month seven: weeks 27-30
Month eight: weeks 31-35
Month nine: weeks 36-40
You start your 8th month at 32 weeks
In Australia it's 35 weeks but most people on this app go by some other method.