(a) If the advisory agency is not authorized by local ordinance to approve, conditionally approve or disapprove the tentative map, it shall make its written report on the tentative map to the legislative body within 50 days after the filing thereof with its clerk.
(b) If the advisory agency is authorized by local ordinance to approve, conditionally approve, or disapprove the tentative map, it shall take that action within 50 days after the filing thereof with its clerk and report its action to the subdivider.
(c) The local agency shall comply with the time periods referred to in Section 21151.5 of the Public Resources Code. The time periods specified in subdivisions (a) and (b) shall commence after certification of the environmental impact report, adoption of a negative declaration, or a determination by the local agency that the project is exempt from the requirements of Division 13 (commencing with Section 21000) of the Public Resources Code.