Ruling 2385
If a woman appoints an agent to marry her to a man for ten days, for example, but she does not specify a starting date for those ten days, the agent can marry her to the man for ten days starting from whenever he likes. However, if it is known that the woman has intended a specific date or time, the agent must say the formula according to her intention (qaṣd).
-Ayatullah Sistani, English Islamic Laws 4th Edition Page 421