How can I notify customers about vacation delays at checkout on Shopify?

[MD-Cha-Ban]

Hallo,
I just migrated my store to Shopify. 
Usually when I go on vacation, I leave my store open and customers could see very clearly in red when 
going to checkout that all order, placed between this and this date, 
would only be delivered when I returned from vacation. 
I'm looking for how I could send a message to customers that would appear at checkout.
I thought of some kind of popups or a very visible line with larger characters.

Do you have any suggestions?

I'm using the Dawn theme.

Thank you for your answers.

[Dan-From-Ryviu · Accepted solution]

Hi @MD-Cha-Ban 

You want to add a pop-up to your checkout page. The Shopify checkout page's customizations are limited, and any coding customizations are available only for Shopify Plus stores. 

But you can add Text field to your product template to announce it

Or add an announcement to the announcement bar