October/November 2011. October 3, the Feminist sperging starts with tricycle girl appearing. November, purple Devil girl/bespectacled nerd love storyline kinda sorta reaches a definite ending with her abandoning Hell and following her desire for a love.
You still have some old Sinfest sprinkled in, but it's a long, long descent into schizo madness afterwards. For 15+ years.
A Sinfest thread on /co/ that didn't manage to get purged by jannies (don't judge, sometimes /co/ has good dumps), beyond people /pol/baiting and drawing weird lewds, made me wonder if Tats would draw his old characters if paid handsomely enough. What would happen if some spiteful bastard dangled enough money before his Asian, broke ass and told him "now you draw cute romcom things. No Jews.".
One wonders.