  We perform a finite-time scaling analysis over the detrapping point of a
three-state quantum walk on the line. The coin operator is parameterized by
$\rho$ that controls the wavepacket spreading velocity. The input state
prepared at the origin is set as symmetric linear combination of two
eigenstates of the coin operator with a characteristic mixing angle $\theta$,
one of them being the component that results in full spreading occurring at
$\theta_c(\rho)$ for which no fraction of the wavepacket remains trapped near
the initial position. We show that relevant quantities such as the survival
probability and the participation ratio assume single parameter scaling forms
at the vicinity of the detrapping angle $\theta_c$. In particular, we show that
the participation ratio grows linearly in time with a logarithmic correction,
thus shedding light on previous reports of sublinear behavior.
