After submit Provisional Patent App on USPTO.gov, how long does it usually to get confirmation of app date?

If you file electronically (which I'm not sure you can do for a provisional) you get confirmation immediately.





If you file by mail, the fastest confirmation you get is if you include a self addressed, stamped postcard listing the papers that you filed by name and page count. (e.g. Provisional Patent Application 20 pages of specification 6 of figures, 3 of claims, 1 of abstract), Transmittal letter, 1 page.). That takes a few weeks.