Yeah, that did occur to me. Hey, you started the thread, so you get to set the ground rules.
OK, so we're back to CWebb/J-Lo. As I recall, Lopez first became famous in the mid-'90s with Selena and Out of Sight, but I don't think anyone was calling her J-Lo at that point. Feels like that probably started late '90s. Webber was famous from his freshman year in '91, but I have no idea when he picked up his nickname. (Personally, I was a huge fan of his at Michigan and never remember calling him that, although I became aware at some point that others did.)
If we're talking about who did the most to popularize the trend, it was Lopez by a mile. But on the narrow question of who was first, I think it was Webber, though I'm not sure.