automate - 300+ customers need to be autopay a few days after the invoices go out.

I have a client that bills once per month.  I want to export the customers that have a checkbox I created that states yes, along with that month's invoice balance to auto-pay credit cards. 

300+ customers need to be autopay a few days after the invoices go out. 

I want to automate by creating a cash receipt import…I am wondering if this will work.  I realize that Paya runs the credit card at the time the invoice is created. 

Are there special steps needed to make this happen

How to automate this?