It's never too ambitious to do anything. I believe CFA is great for a career change as it teaches the very basic of things and then starts to go deeper as you proceed to the higher levels, i.e. Level 2 and 3 without going through the normal degree path.

And since you are sitting for the June 2012, there is still a lot of time for you to be studying. People usually take around 250 hours, so you should arrange your schedule in accordance to that and there shouldn't be a problem in passing at least the first level.

There are jargons but most is already explained in the book while some you might have to find out about the meaning yourself, such as finance terms like securitization, etc....