In the current version the balance check is tied to sending activity rather than a fixed daily schedule: it runs when you open the send confirmation and every time the background sending jobs execute (which is usually many times a day). The auto-recharge itself does not generate a separate advance email; your card is charged when the threshold is crossed. The Payment method box on that card is illustrative — the actual charge goes to the card stored on your Sprwt account. Watch the balance history (Reports > Sales Reports > SMS, reason "Auto Refill") if you want to audit recharges.