BMW blue smoke just a quick puff when starting the car after not running for a few hours any suggestions?

Sounds as if the oil is running past the valve seals on one or more intake valves. After setting for a time, the oil runs down the valve stem and collects in the cylinder head and burns as blue smoke at start up. This is usually caused from the seals being brittle and are split or broken. They are made with an O ring or umbrella shaped rubber material.

Hope this helps.