2,997. Slaughtering a Retroactively Consecrated Animal
Hilchos Arachin Vacharamin 6:9
If someone says that a certain ox will be consecrated after 30 days and he slaughters it within those 30 days, it is permitted to benefit from it. If he consecrated the ox to the altar in this time, it is consecrated to the altar. However, if he says that after 30 days the ox will retroactively be consecrated as of the current moment, then it is prohibited to benefit from the ox if he slaughters it within those 30 days. If he consecrated it to the altar within those 30 days, that consecration is ineffective.
Hilchos Arachin Vacharamin 6:10
If an animal intended for a burnt offering is consecrated for Temple upkeep, the need for the Temple treasurers to appraise it delays the offering. By rabbinic enactment, the animal isn’t slaughtered until it’s redeemed. Therefore, if someone violated this enactment and slaughtered the animal prematurely, it’s still a valid sacrifice.