From which date builder can charge Maintenance charge

I have purchased a flat in Pune at ravet. Project is divided into 3 wings out of that he has given possession of wing C almost 1 year & 8 months back. I have purchased flat in July-16. At the time of entering an agreement I have paid Rs. 10000 against a maintenance charge for a year, which should last till august -17. When I moved in no common amenities are being provided by builder. I was the first person to move in the building. Now builder is saying that since I have given first possession in the month of June, mentainance charges are applicable to everyone from first possession. We were ready to take possessions but entire building was not ready and people have moved in till december-16. As flats were not ready. Now builder is saying that for all people maintence charges will be applicable from the month of June - 16. Till date he has not formed a society & Also he is not ready to handover society till he sale his all flats & on the contrary asking us to take care of the mentainance of B & C wing. Please advise