  In the absence of external forcing, all trajectories on the phase plane of
the van der Pol oscillator tend to a closed, periodic, trajectory -- the limit
cycle -- after infinite time. Here, we drive the van der Pol oscillator with an
external time-dependent force to reach the limit cycle in a given finite time.
Specifically, we are interested in minimising the non-conservative contribution
to the work when driving the system from a given initial point on the phase
plane to any final point belonging to the limit cycle. There appears a speed
limit inequality, which expresses a trade-off between the connection time and
cost -- in terms of the non-conservative work. We show how the above results
can be { generalized to the broader family of non-linear oscillators given by}
the Li\'enard equation. Finally, we also look into the problem of minimising
the total work done by the external force.
