• Adjustment of capital gains on sale of flat

We are NRIs and have booked a flat in June 2016 ( Flat Allotment Letter dated 10th June 2016 ) in Chennai and have paid 25% project cost from own funds. Balance 75% is funded by loan to be paid by FI to builder as construction progresses. Possession is expected in Dec' 2017. UDS ( land share) + Construction agreement registration is scheduled to be done in Aug 2016. We also own 2 other flats in Chennai, one of which is occupied by family and the other is vacant. Ideally we would have liked to sell one of them to part finance the new flat purchase. However, since the resale market is not good now, we have no choice but to wait for another 6 months to sell one of the existing flats. 

My question is, if we sell one house say in Jan / Feb 2017, can the capital gains be offset against the new flat already booked using Sec 54 provisions? Will the new flat booking qualify as 'purchase' for the purpose of being treated as ' purchase one year before the date of transfer...' Under Sec 54? We intend using the sale proceeds of existing house to pay builder the progress construction payments due before possession in Dec 2017 and thereby reduce our loan draw down. Does this proposal qualify for exemption under Sec 54?