In computing any period of time prescribed by or allowed by the panel, the day of the act, event, or default after which the designated period of time begins to run, shall not be included. The last day of the period so computed is to be included, unless it is a Saturday, Sunday, or the applicable local legal holiday in which event the period shall run until the end of the next day which is neither a Saturday, Sunday, or legal holiday. When the period of time prescribed, or allowed, is seven days or less, intermediate Saturdays, Sundays, and legal holidays shall be excluded from the computations. When the rules and regulations in this subchapter require the filing of any paper, such document must be received by the panel or the officer or agent designated by it to receive such matter before the close of business of the last day of the time limit, if any, for such filing or extension of the time that may have been granted.