I was born in 1984, and I was watching Nick since before I could remember. I don't know how, when, or what got me into it. I was probably 3, so it was around 1987 when I started watching it. But definitely by early 1988.
Obviously I missed all the silver ball era. Even after the show vanished in the mid 90s, I've never loved any other Nick show more than YCDTOTV, and that was most definitely old school Nick. Mr. Wizard's World was also seen everyday when I was new to Nick (even though I thought it was boring at such an early age. Now I can appreciate it).
Am I not "old school" because I missed the days of Livewire, Reggie Jackson's World of Sports, Going Great, Lights Camera Action, etc.? Or do you guys count the early orange-and-white days as "old school"?