The purchase is at the time of the expenditure. Using a credit card is the same as taking out micro-loans with every purchase.

The loan is just a funding source. The principal, the same as the credit card balance, is not an expense but debt service paying down the liability.

The interest would be a business expense, assuming the purchases meet the requirement for business interest.

This is why you don't also treat credit card payments or loan principal payments as deductions. They are not expense. They are banking, essentially.

Any legitimate expense for a business is a valid deduction, even if they paid for it with chickens. Creating a loss doesn't depend on how things were purchased. But it can depend on what was purchased.