It's been quite some time for me -- a lot of things in the parks have come and gone or been modified.
But I do remember my last time, in August 1993, the "trigger" as you say was leaving Port Orleans (yes, before the change) and taking the bus over to EPCOT Center (yes, before the change), and looking out the bus window and seeing Spaceship Earth so perfect and so huge (sans wand, yes, before the change) as the bus makes its way off the Disney interstate and to the access road to the parking lot.
Then, right then, I knew my vacation had started. I believe me and my friend's first rides were SSE, then The Land to see Kitcken Kabaret (yes, before the change) and Listen to the Land (yes, before the change) and then to Journey Into Your Imagination to catch Dreamfinder and Figment and Captain EO (yes, before the change).
Hmmm, have to get back to WDW to see what changes were made. But since I have been gone so long from Orlando, I believe I will start next time at Magic Kingdom, because after being away for so long I have to re-start my experience and experience everything that is new. There are many things -- many things -- I need to experience for the first time at WDW. Believe me, Tower of Terror was being constructed in the new wing at MGM, so I have a lot fo catching up to do!
When? Sometime soon, hopefully in the next year. It's been way too long.