Earlier than that. I recall an episode (only saw a clip) of Playboy After Hours from around the late ‘60s/early ‘70s where Hef remarks to Barbi about dating her, and she says to him, “I’ve never dated anyone over 30.” Hef replies, “Neither have I.” ;-)
I find the late 60’s/70’s Playmates to be the hottest. I love the Raquel Filch inspired big hair-dos.
The trend over the last 15-18-20 years of featuring mostly fake plastic Barbie dolls types don't do much for me...