Kylie Jenner's Calendar Got Her Own Birthday Wrong

Kylie Jenner's 20th birthday will be delayed by 10 days this year ... because her own calendar couldn't even get the date right.

The 2017 edition -- sold exclusively on her website -- lists her bday as August 20. Kylie was born on the 10th. On a positive note, there's lots of cake ... on Kylie.

The misprint isn't just a one-off fluke either. We're told it has appeared on multiple calendars since its release a couple weeks ago ... possibly all of them.

As we've reported ... Kylie, inc. was flooded with quality complaints last year, and this ain't a great start for 2017. At least the calendar got her dog's bday right.

Seems like a head or 2 might roll for this -- but Kylie's camp had no comment.