Translation:How long before it is your turn?
It is called "ne explétif", meaning that it is used for the flow of words but does not mean the sentence is negative. to know more: http://french.about.com/od/grammar/a/negation_form_2.htm
What is the reasoning, if any, behing using one of the most important words in any language purely for rhythm, rather than using a meaningless noise instead?
"How long before it is your turn" is a neutral sentence.
"avant que" is one the constructs that gets followed by a "ne explétif" - see the link Sitesurf gave above.
This sentence could easily be: 'until it's your turn' in English, it should be accepted too
""How much time until it's your turn?"" -- is that a different sentence in French? e.g. "Combien de temps jusqu'à ce qu'il soit votre tour?"
The only variant I can think of is: "combien de temps avant que ce soit votre tour ?"
"avant qu'il soit" does not work and an impersonal sentence.
I took the safe bet and translated this as, "How much time before it is your turn?" but I really wanted to try, "How much time before this is your tower'?" Is the latter translation valid?
A bit stretched, isn't it?
But yes, "un tour" and "une tour" cannot be distinguished if the owner is "nous" (notre), "vous" (votre) or "ils/elles" (leur)