If you are a new customer to Klipboard, the best practise is for no Invoices to be created on Klipboard until you have connected your Xero account.

However if you wish to do so please ensure to set the correct Invoice Start number within the Klipboard Settings area so Invoice numbering is aligned with your existing Xero account.

Any Invoices created within Klipboard before you connect with Xero will be synced on the first time connection with Xero.