We've all pulled a Justin at some point in our brewing "careers". Don't worry, make a mental note and do it better next time. Just remember, "it'll still be beer."
As a rule, I don't crack a beer until the boil starts, but then again my boil doesn't usually start until around 5pm, so it's the perfect time

It's a great security measure, but honestly, sometimes my brain just takes a sober crap on me just to spite me. I punish it with beer, and it passes the buck to my liver. It's an endless cycle but we all make up in the end and have a beer together. Oh wait..
Copious note taking will help you get in the habit of starting the clock, recording the numbers, noting volumes, taking temperatures, and all that other stuff. Eventually, it becomes an automatic routine and helps eliminate a lot of stress from the brew day, but sometimes it just slips.
It happens to all of us, eventually.
