How to find a pirate birthday

[JM Ohara]

Okay, I'm sure I'm missing something very obvious here, but how do I find the date I created my pirates on?

I wonder because I started my pirates about three or maybe four weeks ago. I maxed out on basic on June 30th and went unlimited July 1st. Now, just two weeks later my pirates are level 21 and 23. So I kinda wanna know to the day how long it's gonna take me to hit 40. To do that I need my pirates birthday. I just have no clue how to find it.

Any help there? Or should I have written it down the day I did it?