At the first regular meeting after the petition has been filed with it, the board of supervisors shall fix a time for hearing the petition and the protests of interested parties, and shall cause a notice of the filing of the petition and the time set for the hearing to be published pursuant to Section 6061 of the Government Code and not less than one week prior to that time in a newspaper published and circulated in the county in which the district is situated. If there is no such newspaper, copies of the notice shall be posted in three conspicuous places in the territory to be annexed, for three weeks prior to the date fixed for hearing the petition.