Rotating game modes, AKA "Poro King Queue"

I keep checking every Friday in the hope it's URF or ARURF (or, really, O4A, Nemesis Draft, or TT Hexakill), but it's been Ascension or Poro King for...what...over a month, I think? Wasn't it Poro King just LAST WEEK, and here it is again? This is handily my least-liked game mode, but it's all I ever see, it seems like.

When does the "rotating" part come in? How long has it even been since an URF or ARURF was up? is there like a schedule I can check (though cursory searching didn't turn any up) so I can stop being disappointed every weekend? And so I can make plans for shirking responsibilities in advance because I know I'm going to play probably 20+ hours of League in 3 days...