Tds on property

I have purchased a flat of value Rs 52,50,000 as per ready reckner rate & agreement. The formal agreement was done in 20th May 2018 with token amount of Rs 10,50,000 in 4 installements. Further i have applied 37 Lakhs of Home loan. Now i paid all remaining amount of builder (4 installements). But i did not cut/ paid TDS to Govt on each installement. But i have kept 52,500 with me for TDS filling from builder amount. As per procedure , bank will paid loan amount to builder after agreement to sale. Now , 1) in this 2 buyer & 2 sellers are involved & propery is under construction 2) i have paid total 4 installments (Except Home Loan) to builder on 50% 50% share basis, so total 8 transactions involved 3) Home loan of 37 Lakh is applied but bank hold money till agreement to sale Now Question is 1) Do i need to file TDS before agreement to sale (done to be in this week) or Before sale deed (Sale deed will done Nov - 18) ??? 2) if i pay total 8 installements , can i file TDS as lumpsum, because as per this theory i will have to generate 16 challans. ??? 3) Bank loan is not paid yet, so will i need to file TDS on bank loan which is still not paid to seller?