Orders placed after cut-off time

In rare occasions, customers might be able to place an order after cut off times. 
This is usually caused by one of the following reasons.

Abandoned cart

The customer has selected a date, started the checkout process but did not complete it and left your page.

They will then receive an 'abandoned cart' email with a link directing them to the checkout, in order to complete their purchase.

In this case, the date/time they have selected is still saved and they will be able to check out, even after the cut-off time.

To avoid this, the link in the 'abandoned cart' email can be changed to direct to the cart page, instead of the checkout. Your customers will then have to select a new date.

Returning later to finish checkout

Your customer might have started the checkout process and kept the browser's tab open for a period of time before returning and making the payment. 

This means that sometimes they will be able to complete the purchase after the cut-off time has passed.

Unfortunately there is currently no way to avoid this scenario, since the date-picker cannot be displayed on the check-out page.