41 C.F.R. § 302-5.5
Timeframe for completion of the househunting trip
The househunting trip must be completed as follows:
(a) For the employee—the day before reporting to the new Official station.
(b) For the spouse or domestic partner—the earlier of:
(1) The day before the family relocates to the new Official station; or
(2) The day before the maximum time for beginning allowable travel expires.