Sorry, there isn't a way to delay a charge.
Shopify requires the customer to pay for a subscription upfront.
Shopify charges the customer immediately on the day they purchase the subscription and then automatically creates an order.
If the customer is on a monthly subscription plan, they will get charged immediately & then one month later.
If the customer is on a delivery every 2-months plan, they will get charged immediately and then two months later.
If the customer is on a delivery every 3-months plan, they will get charged immediately and then three months later.
Fulfillment: You can let these orders sit until you are ready to ship them out (let's say if you want to ship them all out on the 21st of the month) you can still choose to do that even though your subscription orders are coming in at all different times.
We also have an automatic order tag of ongoing_subscription that will be on all subscription orders which helps sort them on Shopify orders.