Just thought of this today: memorize major world cities and their time zones relative to your own. Not sure how seasonal time changes (summer/daylight saving time) would factor in, but we might also want to memorize when each country/region switches from and to summer time.
In my case, my home city would be Washington, DC, USA. It is usually 5 hours behind GMT, but can be 4 hours behind it if we are on DST but the UK is not on summer time. Cities in your time zone (like Miami, FL and Boston, MA in my case) should probably be memorized first because there’s no change of time for them.