Glucose test

How important is it to have fasted from sugar the night before and the day of the test? I had a  prolly more sugar than I should have yesterday but I can go take the test when ever I want so I was thinking later today!??? I have had just protein so far today. I'm about to make eggs with nothing in them not even milk or salt which I know that doesn't matter but I'm trying to watch it...any other mamas have experience with this? I'm a FTM and not sure if I should wait until tmrw or just go later this afternoon. Thanks for
Your input!