I wrote out checks to pay all the monthly bills yesterday while doing work with my son, who is homeschooled. I was clearly distracted, because I just realized I wrote 10/19 on all the checks instead of 10/12! I already mailed everything, and am trying to figure out what the heck I'm going to do.

Lesson learned. ONE thing at a time!!

It doesn't matter the checks will go through with most likely hundreds of checks (for example: utility payments, mortgage, etc) so it doesn't matter. I have found in my personal experience that I personally have been unable to cash checks for example paychecks that are post dated but when I have written checks for bills and put a future date on it the check has gone through before that date.
If you are worried that this will cause problems call the company tell them you made a mistake and they can go ahead and put the checks through.

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The political system is broke and it's a joke.

Dates on checks don't matter, even if the YEAR is wrong, the bank will still cash them.

Yup.

They've cashed checks that I forgot to put the date on. Heck I think I've forgot to sign a check or two and the still went through.

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Once the game is over, the king and the pawn go back in the same box.

Thanks! My d/h is away, and when I told him, he laughed and said it wouldn't matter.

Clearly multi-tasking is not my strong suit.