Thanks MikeCharlie.
I received the invitation email yesterday; offering the following dates:
Mar 31 - Apr 2
Apr 2 - Apr 4
Apr 14 - Apr 16
I chose the second one.
I traveled from to far to Panama, 6.5hs flight. So I chose a 3 days date. I arrived on sunday morning and I had all day free. then had my dates on monday and tuesday until 4:00pm and my flight back was at 21:40pm. I had time to go to know the Panama Canal and the city.
I don't know from where are you going to, but more time it's better to relax and be fresh for the tests! Of course that's only my opinion.
Very good luck! Regards!
EDIT: HAHAHA sorry, you're from Nicaragua, just a few minutes flight! And I bet you already know Panama...nothing to say! Good luck!!!