  Context. The increased detection rate of Fast Radio Bursts (FRBs) makes it
likely to get samples of sizes $\mathcal{O}(10^2)$ to $\mathcal{O}(10^3)$ in
the near future. Because of their extragalactic origin can help us in
understanding the epoch of helium reionization.
  Aims. We try to identify the epoch of Helium II (HeII) reionization, via the
observations of early FRBs in range of $z=3$ to $4$.
  Methods. We build a model of FRB Dispersion Measure following the HeII
reionization model, density fluctuation in large scale structure, host galaxy
interstellar medium and local environment of FRB contribution. The model is fit
to the ideal intergalactic medium (IGM) dispersion measure model to check the
goodness of constraining the HeII reionization via FRB measurement statistics.
  Conclusion. We report our findings under two categories, accuracy in
detection of HeII reionization via FRBs assuming no uncertainty in the redshift
measurement and alternatively assuming a varied level of uncertainty in
redshift measurement of the FRBs. We show that under the first case, a
detection of $N\sim\mathcal{O} (10^2)$ FRBs give an uncertainty of $\sigma
(z_{r, fit})\sim0.5$ from the fit model, and a detection of $N\sim\mathcal{O}
(10^3)$ gives an uncertainty of $\sigma (z_{r, fit})\sim0.1$. While assuming a
redshift uncertainty of level $5-20\%$, changes the $\sigma (z_{r,
fit})\sim0.5$ to $0.6$ for $N\sim 100$ and $\sigma (z_{r, fit})\sim0.1$ to
$0.15$ for $N \sim 1000$ case.
