S01 E01: when Dan is sitting at his laptop while the "xoxo Gossip girl" v.o. is happening
S02 E25: High school grad when Serena invites GG to one oak and Dan shows up first
S05 E22 (I think) when they're tracking GG's phone and Dan shows up at the brothel/mansion https://twitter.com/eggshellfriend/status/1264765256196403202

I think by S5 they realised they wanted to make Dan GG so they made the situation more obvious. I'll say that they likely had a different intention in the beginning. Making Dan GG felt lazy yet made sense the more I watched this show. Yes, I too hate myself for this thread.