We have our existing invoice number format, and although we can amend the format of this going forward, it makes no sense to begin invoicing again at number 1! It would certainly be useful to have a configuration parameter where you can specify what number to start from, and then let that be overridden if necessary. We simply couldn't start from invoice 1 again as we already have invoice number 1 which was generated years ago...
Thank you for feature request. Until this functionality is developed we can manually modify the starting invoice number. If you would like to do that, please log into your account and hit the feature request link in the footer and let us know what the starting number should be and we will manually change the start number.