Theres always confusion in these cases.
There is this case of C.R.Subramanian where, the assesse HAD the land and he constructed BUILDING thereon.Lateron he sold such PROPERTY.
It was held that period of holding should be reckoned on individual basis and therefore Land was chargeable to LTCG whereas Building was charged to STCG.
But the facts of your case are different.
Legal fiction
What the buyer is Purchasing is not a part of land or part of building, he is Purchasing the residential unit. Therefore date of transfer as per 2(47),read with sec 53A of transfer of property act, is date of possession.
S 53A basically says right in the property will be of tranferee
"Where any person contracts to transfer for consideration any immoveable property by writing signed by him or on his behalf from which the terms necessary to constitute the transfer can be ascertained with reasonable certainty, and the transferee has, in part performance of the contract, taken possession of the property or any part thereof, or the transferee, being already in possession, continues in possession in part performance of the contract and has done some act in furtherance of the contract, and the transferee has performed or is willing to perform his part of the contract, then, notwithstanding that the contract, though required to be registered, has not been registered, or, where there is an instrument of transfer, that the transfer has not been completed in the manner prescribed therefor by the law for the time being in force, the transferor or any person claiming under him shall be debarred from enforcing against the transferee and persons claiming under him any right in respect of the property of which the transferee has taken or continued in possession, other than a right expressly provided by the terms of the contract: Provided that nothing in this section shall affect the rights of a transferee for consideration who has no notice of the contract or of the part performance thereof"
(This is basically for seller)
The above is created by legal fiction, the courts are taking the substance of transaction into consideration
U.P. State Agro Industrial Corporation (supra)
"The assessee will be considered to be an owner of the building under Section 32 if he is in a position to exercise the rights of the owner not on behalf of the person in whom the title vests but in his own rights"
(They were allowed to take Dereciation on the asset which was not in their name.)
Text from CIT vs R.L. Sood
The date of agreement of purchase should be taken as the date of purchase
Also making referrence of DDA because what DLF does is akin to this. (Board Circular No. 471)
Under the Self Financing Scheme of DDA, the allottee gets title to the property on the issuance of the allotment letter and the payment of Installment is only a follow up action and taking the delivery of possession is only formality. If there is a failure on the part of DDA to deliver the possession of the flat after completing the construction, the remedy for the allottee is to file a suit for the recovery of the possession. Therefore, for the purpose of capital gain tax, the cost of the new asset is the tentative cost of construction and the fact that the amount was allowed to be paid in Installments does not affect the legal position stated above.
[https://www.incometaxindiapr.gov.in/incometaxindiacr/contents/CBDTFiles/Circulars/CBDTLaws/HTMLFiles/sec54_672_93.htm]
In short, when you receive the letter of allotment you have purchased/acquired the property.NOT THE DATE OF POSSESSION
Period of holding is to be considered from such date. This is your date of purchase/acquisition
I will be Glad to read other view points with some supporting