How long does a 30 Day Admirals Club membership take to take effect?

How long does a 30 Day Admirals Club membership take to take effect? I'm considering buying it to use on a trip, departing 19 Jan. It's USD 99 for lounge access at Qantas Clubs - is it worth it?

Thoughts are much appreciated.

Watson,the Admirals club pass you refer to takes effect from the date you purchase it or at the time you purchase you can nominate a date that works with your schedual and is with in 90 days of the date of purchase. You can not change the date after purchase.It good value as far as US airline lounges go and you receive all the benifits that come witha regular admirals club memership.Check out aa.com.

I also add that if you are a QF club member or above and traveling on American that day you can access aa lounges-hence no need for a pass.

Sorry, I should mention I intend to use it only for the reciprocal benefit of QP access, in order to gain QP access over my trip of about a month, without buying full QP (as I OLCI).