When should I return the empty cylinders from the subscription?

When you are on the subscription plan you will need to return the cylinders after the number of months you have chosen PLUS 30 days. If you do not return the empty cylinders within this timeframe, or if you do not have any empty cylinders to return, or if the returned cylinders are damaged, we will automatically charge you £10 for each unreturned or damaged cylinder.

You do not need to return any cylinders until the 2nd shipment has been made. Or if the subscription has been cancelled before the 2nd shipment was made.