Your account is automatically debited 45 days before the domain’s expiry date.
If you decide to activate the auto-renewal feature after the 45 day limit but before the domain is due to expire, the charge will be made within 24 hours after the activation of this service.
Please note that auto-renewal is not available for expired domains and that that you will need to renew them manually using the “Late-renewal” option directly in your Nominus.com account.