I have a field on the checkout page of my Drupal Commerce webshop.
The user can pick a date for delivery.

The problem is that the date isn't formatted correctly. It should be dd-mm-yyyy, but it is mm/dd/yyyy. I have a correct date display created.

The strange thing is that when you select the date, and you go to the checkout page, the delivery date there is correct.

What i also would like to do, is to make it inpossible to select a date in the past, and disable the days that the store is closed.

I have searched and found some possible solutions, but i can't seem to get it to work. Any help/tips would be appreciated!

Thanks for your help.