31 CFR §555.302

1. (a)The term effective date refers to the effective date of the applicable prohibitions and directives contained in this part, and, with respect to a person whose property and interests in property are blocked pursuant to § 555.201, the earlier of the date of actual or constructive notice that such person's property and interests in property are blocked.
2. (b)For the purposes of this section, constructive notice is the date that a notice of the blocking of the relevant person's property and interests in property is published in the Federal Register.