Taxation on advance consideration received and sale agreement is in next FY year

I am selling my land to one person, for that he has given me some advance payment in(FY 21-22)and told me that transfer of asset(sale agreement) will take place in next FY year (FY 22-23).

Do I need to pay capital gain tax on that advance amount received while filing ITR in the current year(part payment), and for next FY year when the sale agreement will take place pay the capital gain tax on the remaining amount which I will be getting after transfer of asset.??? 

If yes then I might expire the window of 6 months for exemption u/s 54EC

BUT, As the law of ITR says, the capital gain has to be paid in the same year of transfer of asset. 

Need the opinion of experts.

Thanks