Invoices are usually e-mailed or occasionally snail mailed to customers. I try and get them done within a month of delivery but sometimes it may take longer because I don't always get paperwork on time from David. I invoiced every job for 2014 (150+). and informed everyone that you would get one.
I always specify in emails that it is your responsibility to keep these invoices for your records.
If you request duplicates later I indicated you will be charged a fee. The policy was posted on right side bar of blog as of January 2014 and is still posted for your reference.