After the council fixes the time and place for said hearing on the assessment roll, the clerk of the municipality shall give notice by publication in the official newspaper of such municipality in three (3) successive issues if published in a daily newspaper, or by publication in two (2) issues if published in a weekly newspaper, the first of which publication shall be at least fifteen (15) days before the date fixed for hearing objections to said assessment roll, that such assessment roll is on file in his office. The notice shall further state the date, time and place at which the council will hear and consider objections to the assessment roll by the parties aggrieved by such assessments. The clerk shall, not less than fifteen (15) days before the date fixed for hearing objections to said assessment roll, mail a substantially similar notice to each owner of property if known, or his agent if known, within the limits of the improvement district, addressed to such person at his post office address if known, or if unknown, to the post office in such municipality where the improvement is to be made. The mailed notice shall also state the amount of the individual assessment and that at the specified time and place the council will hold a hearing to hear and determine all objections to the regularity of the proceedings in making such assessment, the correctness of the assessment, and the amount levied on the particular lot or parcel in relation to the benefits accruing thereon and in relation to the proper proportionate share of the total cost of the improvements in the project. It shall further state that each owner of property within the district is given notice that in revising the assessment roll at or after the hearing, the council may increase any assessment or assessments up to twenty per cent (20%) of the original amount thereof without giving further notice and holding a new hearing thereon. The owner or owners of any property which is assessed in such assessment roll, whether named or not in such roll, may, before the date and time fixed for the hearing, file with the clerk his objections in writing to said assessment.