From when do maintenance charges of flat apply from

What is the date of start of maintenance charges (for common areas) in case of a ready to move property? It is specifically mentioned in my buyer builder agreement that, "the maintenance charges shall be payable by the purchaser/s from the date of offer of possession irrespective of whether the possession is taken and irrespective of whether the apartment is occupied at anytime or not". The builder is demanding maintenance charges from date of booking, citing reason that, "The maintenance charges are applicable from date of offer of possession of the Apartment in Under construction Apartments only In your case the apartment was ready to move in so in your case the maintenance charges starts from the date of booking."