The board shall meet at the office of the county controller not later than noon of the third Wednesday after the first Monday of January following the election of the county treasurer, and thereafter as may be necessary, and shall there decide upon the number of banks and banking institutions, not less than three in number, as depositories of county funds, for such period of time as the board may determine, but not to exceed the term for which the treasurer is elected.
16 P.S. § 4962