12 C.F.R. § 221.102
Application to committed credit where funds are disbursed thereafter
The Board has concluded that the date a commitment to extend credit becomes binding should be regarded as the date when the credit is extended, since:
(a) On that date the parties should be aware of law and facts surrounding the transaction; and
(b) Generally, the date of contract is controlling for purposes of margin regulations and Federal securities law, regardless of the delivery of cash or securities.