I was wondering if anyone can guide me, I'm contemplating taking an immersion class, either here in the U.S., or in another country for about three weeks. I really need to get up to conversation level as soon as possible for employment reasons.

What is the best route to take? Has anyone taken one of these courses without having any other formal lessons? Is this something that is going to get me into the flow, or just a waste of my money for so short of a time frame?

Any recomendations on what to do?
I only can comment this: it's a very short period of time, you won't take too much from this. You'd better think in a period of six months, no less.
I Agree. But, if you have the chance, immersion is the best way to go, nothing compares when you must use day to day.

Good luck