When you set up automatic payments with a credit card, we don't store customer credit card information. The card information you submit goes directly to PayPal and then, in turn, is set up for the recurring payment in their system. 

Thus, the best way to change your auto-pay credit card is to go to our Billing page (https://triplogmileage.com/web/billing/currentBill), then click the "Turn off auto pay" button. Next, click "Pay Next Bill" button, turn on Auto Pay switch, and pay with the new credit card.  This will charge your credit card for your upcoming bill and set up the recurring payment for subsequent bills.

You can pay now or wait until the due date.  There will be no difference.  Your subscription date stays the same.