I was just prescribed 0.5mg of Ativan. How long will it take to work, and how long will it stay in my system?

I've had an anxiety disorder for a long time now, and it's definitely at it's worst right now. I'm now afraid to do things that never bothered me before, so my doctor prescribed me tablets of 0.5mg of Ativan, and told me to take them as needed. How long will it take to work and how long will it stay in my system?

: http://alcoholdrugstreatment.info/i-was-just-prescribed-05mg-of-ativan-how-long-will-it-take-to-work-and-how-long-will-it-stay-in-my-system