In a typical delayed exchange, replacement property must generally be identified in writing within 45 days after the transfer of the relinquished property. The period isn't extended for weekends or holidays, and the identification has to satisfy the requirements your qualified intermediary explains — including unambiguous description and proper delivery.
The practical problem isn't the rule. It's that 45 days of calendar time is not 45 days of usable search time. Touring, underwriting, negotiating and inspecting takes longer than most owners expect, especially in an unfamiliar market or asset class.
The owners who do this comfortably start looking before the relinquished property closes. By the time the clock starts, they already know the markets they're interested in, the economics they need and which professionals are helping them evaluate each candidate.
The regulations also describe identification alternatives commonly summarized as the three-property rule, the 200-percent rule and the 95-percent rule. Which one you rely on is a strategy decision. Confirm it with your qualified intermediary before you submit anything.