At any time before 10 a.m. on the Monday next after the expiration of 20 days after the date of service of the notice to designate, the judgment debtor may designate the homestead as defined in Section 41.002 by filing a written designation, signed by the judgment debtor, with the justice or clerk of the court from which the writ of execution was issued, together with a plat of the area designated.
Tex. Prop. Code § 41.022