For me it was when I finally saved enough money to upgrade my 8088 in 91. Bought a Computer Shopper, picked out all the parts I needed, went with a 386 DX/40 1 Meg of Ram (I think) and a new case.
The rest I transferred over from my 8088, had VGA, Soundblaster 1.0, 40 Meg RLL Harddrive, and something else I can't remember.
Got all the parts in, put it all together and turned on first time I tried it, was booting back into DOS (Unlike if you transferred a hard drive to a new machine today) and was back playing all my games, plus some new ones I had got that didn't run on the 8088.
Was an amazing time, and so glad that everything just worked.