Treatment of interest on NSC

I purchased NSC worth Rs 3.5 lakh on 18/06/2020. I will claim rs. 1.5 lakh u/s 80C in F/Y 20-21.
How should I treat the interest thereon? In which f/y should I claim the interest on NSC u/s 80C for the first time as the interest is treated to be reinvested in the same section?
Should I have to calculate the interest from 18June 20 - 31 March 21? If I do so then interest will be bifurcated into 6 financial years instead of 5 years. Pls tell me how to treat it.