The NHL roster freeze starts at 11:59PM on December 19th and ends at 12:01PM on December 28th. (John Shannon)
The Rangers have four games in that time, 12/20 against the Islanders, 12/21 against Minnesota, 12/22 against Toronto and 12/27 against Washington.
Per the NHL CBA “For all Players on an NHL Active Roster, Injured Reserve, or Players with Non-Roster and Injured Non-Roster status as of 11:59 p.m. local time on December 19, a roster freeze shall apply through 12:01 a.m. local time December 28, with respect to Waivers, Trades and Loans; provided, however, that Players may be Recalled to NHL Clubs during this period and, provided further, that if a Player is placed on Regular Waivers prior to the roster freeze period and is claimed during such roster freeze period, the roster freeze period shall not apply and the Player shall immediately report to the claiming Club. However, during the roster freeze period a Club can make any Player transactions necessary for the Club to come into compliance with Article 50 as a result of a Player being removed from the Bona-Fide Long-Term Injury/Illness Exception.”