Coming as a fresh off the boat 6yo Soviet, I was blown away by the fact that there were ads on the telly and was mesmerised/obsessed by them for yonks.
Googles... 1991. When they started including listings for ITV/C4* in the Radio Times. We literally didn't watch the other channels before then, so the concept of adverts was new.
How old were you when you first realised that the BBC don't just put in adverts in the middle of programs like ITV/Channel 4 etc?