(a) General priority rules. Except as otherwise provided in this section, priority among conflicting security interests and agricultural liens in the same collateral is determined according to the following rules:
(1) Conflicting perfected security interests and agricultural liens rank according to priority in time of filing or perfection. Priority dates from the earlier of the time a filing covering the collateral is first made or the security interest or agricultural lien is first perfected, if there is no period thereafter when there is neither filing nor perfection.