Turn hours into a draft invoice
Log the hours against a client. Select the ones not yet billed, and Wire Invoice drafts an invoice from them.
Log the work first
On Track, enter the client, what you did, the hours, and the rate. Nothing is sent to the client at this step.
Then make the draft
Select the unbilled rows and turn them into an invoice. Hours become the quantity. The invoice is a draft, with its own number. You still check it and send the PDF or the link.
Billed hours stay billed
Those rows are marked billed, so the next invoice does not charge them again.