ITR2 income tax return

An advance has been paid to the builder for an under construction flat from the sale proceeds of residential property to avail capital gains tax concession.

The remaining cost of the flat is parked in capital gains account under section 54 of IT Act.

1) How to show the split between the advance payments and the balance in the capital gains account as on date of filing the return?

2) What is the date of purchase of the asset? Can we take the date of allotment as the date of purchase or the date of payment of first installment of advance payment as date of purchase of the flat?

Thanks in advance