i dont usually drink energy drink, but when i do i prefer 5 hour energy.
Seriously that thing did the trick for me TWICE. I took my test ~8 so i took the 5 hour energy before signing in and i was not tired at all during/after the test. Plus it is a small shot unlike other drinks so you wont have sudden urge to go to the bathroom. I didnt eat any breakfast when i took mine since i wanted as few "possible disturbances" as possible during the test. I would steer away sugary drinks since you might crash during the test - 5 hour energy has no sugar and supposedly doesnt cause crashes. If I were you I would buy one from a store and try it out on a semi busy day and see how it goes.
If you like my answers please +1 kudos!