Section 354 - Preparation and filing of tentative budget1. The budget officer, upon receipt of the estimates of the various administrative units and the requests for an appropriation of the several authorized agencies, shall proceed to make such review and investigation of such estimates and requests and conduct such hearings of heads of administrative units and authorized agencies, and officers and employees thereof, as he deems necessary. He may require the head of any administrative unit or authorized agency, or any officer or employee thereof, to furnish data and information and to answer inquiries pertinent to such review or investigation. Members of the committee of the board of supervisors designated or created to review the tentative budget shall be entitled to investigate and make inquiry concerning the estimate of any administrative unit or the request for an appropriation of any authorized agency. Such members shall be entitled to attend all hearings conducted by the budget officer pursuant to this subdivision. At least twenty-four hours' written notice of any such hearing shall be given to such members by the budget officer, either personally or by mail.2. Upon the completion of the review and investigation of the estimates of the various administrative units and the requests for an appropriation of the several authorized agencies, the budget officer shall prepare a tentative budget, accompanied by a budget message where required pursuant to section three hundred seventy-four. He shall cause to be printed or otherwise reproduced such number of copies of such tentative budget and such budget message, if any, as the board of supervisors shall direct. The tentative budget and the budget message, if any, together with the copies thereof, shall be filed by the budget officer with the clerk of the board of supervisors not later than the fifteenth day of November.3. The board of supervisors by action taken pursuant to section three hundred seventy-six may require that the budget officer file the tentative budget and budget message, if any, with the clerk of the board of supervisors on or before a specified date prior to the date prescribed in subdivision two of this section, provided that in no event shall such filing be required to be made prior to the first day of October. A local law adopted pursuant to this subdivision shall not become effective until August first next succeeding its adoption.