The City Manager shall prepare and submit to Council at its first January meeting an appropriation ordinance containing a financial plan for conducting the affairs of the municipality for the ensuing year. Council shall by ordinance specify the form of and information to be included in the appropriation ordinance. Council may amend such ordinance in accordance with its judgment and discretion. The appropriation ordinance may be passed upon a single reading and shall become effective forthwith on its adoption or at the earliest date provided by law.