Reverse planning, also known as backward planning, is a simple concept that took me a long time to learn.
I was raised in a very "casual" family where 90 minutes late, to family gatherings, was considered on time. Sometimes, we'd arrive at Mass after the Gospel (very late into the liturgy). The Marine Corps was less tolerant of tardiness; 15 minutes early was considered on time. In the military, being late is referred to as UA/AWOL – a punishable offense.
I had two key experiences in the Marines that got me focused on time management. Reverse planning is a cinch once you learn it since it requires minimal attention. Simply start with a place you need to be, by a certain time, and work backward.
12:30 PM: Airline flight departs.
12:00 PM: Airplane begins boarding (unless it's Alaska Airlines, they begin boarding 45 mins early).
11:30 AM: Allow 30 minutes to get through security.
11:15 AM: Allow 15 minutes to get your boarding pass and check-in your baggage.
10:55 AM: Give yourself 20 minutes to park and walk into the terminal.
09:10 AM: Drive to the airport. Give yourself an extra 50% for traveling. So, if it typically take 30 minutes to drive to the airport, then give yourself 45 minutes.
09:00 AM: Allow ten minutes to gather your stuff and load it into the car.
8:00 AM: Reveille, reveille! Wake up at 8 AM if it typically takes you 45 – 60 minutes to shower and get dressed. Add an hour or so if you need to pack.
There's nothing difficult about reverse planning other than having the discipline to do it and being honest on your time allowances. I frequently do it, even for trivial events, to keep my skills sharp.