Dear Sir,
For the computation of capital gain firstly it has to be determine that whether the asset is a long term capital asset or short term capital asset.
As per section 2(42A) of income tax act 1961, “short-term capital asset” means a capital asset held by an assessee for not more than thirty-six months immediately preceding the date of its transfer.
In your case the counting of 36 months will start from the date of allotment, the date of possession is not relevant as per the judgement in case of Meena A. Hemnani, Mumbai vs Assessee on 9 January, 2014.
There will be no difference in computation of tax whether the property is sold prior or after the possession.