Taxation of sale of share of unlisted co(long term)

Hello,

Need to understand tax liab on sale of shares of unlisted co, there are long term capital gain(shares held >24 months), to save tax 54F suggest for investment in resi property(ready or U/c-2 or 3 years respectively), If we put money into under construction property which will take approx 2-2.5 years, cap gain is already occurred but post allotment letter of apartment, now demand from builder may be post 12 months, capital gain will keep arising during year from sale of shares, how to adjust this/how to show in ITR/what tax liability is there or no tax liab if full gain invested in apartment, how to treat cap gain income occurred now but builder demand may come in Dec 2020.

Thanking you!!

Regards

Ramesh Mundra