25 Pa. Stat. § 3150.15
The county board of elections, upon receipt and approval of an application filed by a qualified elector under section 1301-D, shall commence to deliver or mail official mail-in ballots as soon as a ballot is certified and the ballots are available. While any proceeding is pending in a Federal or State court which would affect the contents of any ballot, the county board of elections may await a resolution of that proceeding but in any event, shall commence to deliver or mail official mail-in ballots not later than the second Tuesday prior to the primary or election. For applicants whose proof of identification was not provided with the application or could not be verified by the board, the board shall send the notice required under section 1302.2-D(c) with the mail-in ballot. As additional applications are received and approved, the board shall deliver or mail official mail-in ballots to the additional electors within 48 hours.
25 P.S. § 3150.15