If you've had these accounts for about 40 years, why don't you know the approximate due date for your Strawbridge's account?

I've had a Kohl's charge for about 15 years, and it's ALWAYS due on the 18th. They don't send a bill if the balance is 0. If it gets close to the 18th, and I haven't received a bill, I call the number on the back of the card to make sure there isn't a balance due.

See, Kohl's has this terrific billing system: I pay my bill on the 18th. If I buy something on the 18th, it shows up on my bill the next month. But if I go back on the 19th, it won't be due until the month after next! There's no interest accruing.