Many years ago I bought 2.2lbs of 100% caffeine powder. I still have about 2.1lbs bagged up in the freezer. It’s handy for mixing in drinks but for my money not as good as just regular old Walmart brand caffeine pills:
Last time I bought those I got carded! Ha! We’ve come a long way from being able to buy enough caffeine powder to kill an elephant to being carded for buying stay-awake pills. 
Anyhow, I just take one 200mg caffeine pill 30 minutes before the gun along with a gel. 4 hours later, I take another caffeine pill. 4 hours later, another caffeine pill.