What should I enter into the start date field for my surgery countdown ticker?

I'm wanting to use my ticker in reverse... to show how much time has past since my surgery. In my case, it's been 4 months, 2 weeks, and 3 days.

If I enter my surgery date for both fields (start date / surgery date), the ticker won't work and I get a message saying so.

Not knowing what date to enter, I put my birthday, which is why I have a gap of twenty thousand or so days from the beginning of my ticker to my surgery date.

I hope I explained myself well enough and, hopefully, my question makes sense.

"Time until "app does both, if I looked it would tell me how long it's been since mine.

I just want to know what others have in their starting date field. Mine works, too, but it also looks a little ridiculous with a starting date 20,000+ days prior. Also, it didn't change automatically until I went back into the ticker options and resaved. I am not going to resave every day for it to work!