TMEP § 303.02(a)
When a document is filed electronically, the USPTO generally receives it within seconds after it has been submitted. Upon successful submission, the trademark electronic filing system almost immediately displays a page that confirms receipt. This page may be printed or copied-and-pasted into an electronic record for storage, and used as evidence of filing should any question arise as to the filing date of the document. See TMEP §303.01 regarding the filing date for an electronic submission.