Invoice Draft Number Problem

Invoice Draft Number Problem

Good morning,
i have a zoho invoice standard subscription, and i have a huge problem with invoices, if i create a draft of invoice the number of invoice is reserved for this draft.. but i need that the number is assigned when the status of invoice changes from draft to active.. is possible?
An other solution in my case is to create an estimates from the projects time entries (not an invoice draft).. Is There any solution?

Your sincerely, Marco