I want to know when I have created Facebook account. There are so many ways defined on net. I used following method, it may help someone also

Login into facebook account.
On top click on your small profile photo, it will open your facebook profile page.
Now scroll down page until your profile and profile background image go off the screen.
You will see three column drop down menu on left side Showing three button 1.) Your Name 2.) Timeline 3.) Recent
Click on Recent and click oldest year.
It will shows you born on ...
Now click Show SomeYearRange just above to it e.g. in my case it was Show 2016 - 2017
It will show your first post when account was created.