So is the concensus that we ( professional aircrew) should anticipate this issue and similar issues by mentioning it in our pre-Flight Annnouncement from the Flight Deck?
I would have thought that it would be far more sensible for the CC to mention it it when necessary, as they can see it occuring and their workload already includes repeatedly issuing a "welcome, stow your hand luggagge etc" greeting to the pax.
All they would need to say is something to the effect "the captain has turned on the air conditioning system for your comfort and you may notice some white condensation coming out of the air vents, this is perfectly normal and will stop when we reach our cruising altitutde."
Sounds to me like a cabin crew training matter, not a flight deck matter.