Merchandise is ordered on June 13; the merchandise is shipped by the seller and the invoice is prepared, dated, and mailed by the seller on June 16;

Merchandise is ordered on June 13; the merchandise is shipped by the seller and the invoice is prepared, dated, and mailed by the seller on June 16; the merchandise is received by the buyer on June 18; the entry is made in the buyer's accounts on June 19. The credit period begins with what date?