I have mine today too. Kinda nervous. I ate breakfast and going in just before lunch. My doc said a 3 hour fast is fine.

they will weigh u, check blood pressure, then you'll drink either a fruit punch or orange drink & go wait in the waiting room for an hour. then your doctor will see u, check ur stomach ask u questions etc. measure ur stomach, then you will go get ur blood drawn to check glucose levels. you do need a snack for afterwards because I almost fainted.

Make sure you bring water and a snack to eat right after, you'll probably feel pretty awful after