Okla. Stat. tit. 6, § 602.1

If a bank, credit union, or savings association has one or more detached facilities or branch offices or deposit production offices or loan production offices, those facilities, branches, or loan production offices may be open at times and on days which are different from the hours and days the main office is open, as specified in the organization's plan. Notice of a change in hours or days of operation should be furnished to customers to the extent practicable.