Flat Agreement - 1st Applicant Vs 2nd Applicant

Hello Experts, There is a under constructed flat which is on the name of i.e. 1) 1st applicant : My uncle 2) 2nd applicant : my self. We will be receiving possession in April'2016. NOTE-The total flat cost has been bear by myself. The reason we kept uncle's name as first owner because the said flat he/we had won in one lucky draw system organized by one of the trust. However, my uncle was not at all interested to invest any fund in this and he advise me to buy the said flat by adding my name as 2nd co-applicant. Hence I have made the whole amount for the said flat. Now I am seeking advise from expert how and what steps legally I have to follow to avoid any future issues. Also which is a good time to prepare and execute the documents i.e. Before possession OR on the time when society will get formed. Please provide your valuable suggestion so that in future I can sale/transfer this flat with my own will and wish. No involvement of my uncle in future. Also I would like to have my name only when society will get formed.