All SSRIs work differently for different people. What may work for one person could not make a difference for someone else. Just because Zoloft didn't work for you doesn't mean it will be the same with Prozac.
I take 40 mg of Prozac, and I would say my HA has decreased GREATLY. I was a mess months ago. I have OCD, and it seems my obsessions have switched from HA back to germs. I can't say if the Prozac helped, or my OCD just switched. Anyway, my family sees a difference in my over all mood.
I personally would wait until I returned from vacation to start taking it, because you may have some start up side effects. I was nauseous when I first started Prozac at 10 mg. You don't want anything ruining your vacation! Relax and just take it when you get back home.