Capital gain on sale of under construction property

In case of sale of a property after possession, which was alloted by the Builder / Real Estate Developer in under construction stage, whether the holding period will include the period of construction after date of allotment  till date of possession and the period the asset was held after date of possession till date of sale for the purpose of calculation of Capital gain? OR whether the holding period will commence only from the date of possession (execution of conveyance deed by Builder)? What is legal position? Please guide me at the earliest. Thanx and regards