Black Mamba drink effects?

I am a 13 year old girl running a track meet tomorrow and I know that I shouldn't be drinking energy drinks, but I am not able to get a nutritious breakfast tomorrow due to schedule stuff. If the track meet starts at 2:00 pm when should I drink the Black Mamba? I don't want to have to pee in the middle of the race, but I want the drink to kick in at the right time.