Estimate parameters in $y=y_{0}(1-\frac{t}{\tau})e^{-\alpha t/\tau}$

Estimate parameters in $y=y_{0}(1-\frac{t}{\tau})e^{-\alpha t/\tau}$

Given the function $y(t)$ with two independent parameters $\tau$ and $\alpha$
$$ y=y_{0}\left(1-\frac{t}{\tau}\right)e^{-\alpha t/\tau}, $$
if we have three data points (experimental data) $
(t_{0},y_{0})\,,(t_{1},y_{1}) \mbox{ and } (t_{3},y_{3}) $.
What is the best way to estimate $\alpha$ and $t_d$?