When a student pays for their membership on a specific day (e.g., the 18th), their billing cycle starts from that date, so they’ll be charged on the 18th of each month going forward.
However, as a gym owner, this doesn’t affect you directly, you can still choose to receive all payments on a specific date or manage your cash flow as you prefer. This setup just needs to be configured through Stripe, where you can decide when and how you want to collect the funds.