Capital Gain tax on flats sold through development agreement

Hi, I(landlord) have entered into a development agreement with a builder on 1st-June-2015.During filing returns for AY 2016-17 i have showed the long term capital gain arising out of the transfer of undivided share of land to builder(Calculated using the share i received in sft * Construction cost per sft) and paid the corresponding long term capital gains tax. As per this year budget any immovable property sold after two years of holding will be considered as LTCG tax.My Question is if i sell my share of flats after 1st-June-2017, will the profit earned after deducting the Cost of construction(shown a LTCG during previous IT returns filing) & land value of UDS of that flat(LTCG now) will be considered as LTCG or STCG? To put my question other way what is the date considered to come to a conclusion if the gain is LTCG or STCG i.e.2 years from date of registering development agreement (or) 2 years from date of completion and hand over of flats by builder.In my case i have already showed the date of transfer as 1st-June-2015 and paid corresponding LTCG tax. Regards Vijay