I do not believe that schooling is by any means the correct choice to make when wanting to break into the industry.
It is too expensive for getting a job in an industry that pays too little, and it isn't required except for certain jobs that you won't get anyway without a lot of experience.
I think the earliest schooling in brewing should be considered is after a year of experience. You might not like brewing professionally, you will have a better idea of your earning potential with and with out the schooling and thus better able to make an informed decision about whether or not it is financially feasible for you to pursue.
Brewing school should not be used as a "foot in the door" type move. I don't believe it is a great way to go about it. A much much much better way to get a brewing job is not by responding to a posting on ProBrewer, because tons of people out there obviously already know about it so your competition will be huge, and brewing school may not be enough to differentiate you from your competitors. The best way to get a brewing job is from word of mouth from other brewers. Make friends with as many brewers as you can. When many brewers are looking for someone, they'll tell some of their buddies in the industry about it. If you are good buddies with a brewer, and he knows you are looking, and you have fed him some damn good homebrew, he may just tell you about a job he heard about that may be opening up soon.
The way you get a job in a hobby industry like this is by getting the job before it is even posted publicly. There is simply too much competition out there for you to get a job from postings within a reasonable time frame.