timed delay in sending invoiced/superbills

I realized I made a typo in the amount, and there is no way to edit it mow that it has been sent. It would be great to have a window to edit or delete invoices prior to them being sent. The instant send has been a challenge and has caused issues several times. This would also be helped by having a specific client’s rate set as a default (some are sliding scale, some get charged a travel fee, etc). Thanks!