glucose test

Des • 2nd pregnancy due Feb17'! Back to back pregnancies- first baby will be 1yr old Jan 15 💗 #teamgirls
Is it too late to take the glucose test at 31 weeks? When is this suppose to be done?
Second pregnancy and I don't remember how many weeks I was when I did it last time. My doc just made me do it one apt but this time around I been rescheduling a lot due to work and being out of town esp with my 11 month old my schedule gets tied up😭