For PayPal, we create a Billing Agreement in PayPal. The First Payment and subsequent date is a day after they sign up day. This is expected behavior and is due to PayPal integration API.
You can see their documentation: https://developer.paypal.com/docs/api/payments.billing-agreements/v1/#definition-create_agreement_request
In particular:
start_date string required
The date and time when this agreement begins, in Internet date and time format. The start date must be no less than 24 hours after the current date as the agreement can take up to 24 hours to activate.