Once a new strain of common cold (human rhinovirus) had arisen in one place, how long do you think it would take; in this day and age of travel and over-population; for it to have spread all over the planet?

I guess the same as with the 2009 flu pandemic.

It has been noticed in April 2009 and was at peak some months later (in autumn on the northern hemisphere)

http://en.wikipedia.org/wiki/2009_flu_pandemic