In computing any time period, the last day of the period shall be included, unless it is a Saturday, Sunday or legal holiday, in which event the last day shall be the next day which is not a Saturday, Sunday or legal holiday. Any time period may upon application of a party be enlarged for good cause shown, for the doing of any act, other than the 30-day time period within which a notice of appeal must be filed. Whenever a party is required or permitted to perform an act within a prescribed period of service of a paper upon such party, and the service is by mail, three days shall be added to the prescribed period.
N.Y. Comp. Codes R. & Regs. Tit. 6 § 647.13