Blue smoke should come from oil.
You don't need that much to get the smoke.
With turbo diesels it comes most of the time from the turbo bearing. With petrols: valve sealings.
Reasons: wrong grade of oil (to thick/to thin, both can cause this), not letting the engine warm up after cold start, not let the turbo cool down after a hot ride (most common reasons).
A little bit of blue smoke only when cold is not dramatic.