If you're gonna do the approved course, I don't think it would be money well spent to get an IMC before hand. It's like doing a PPL before a 509 course--might be handy to have a bit of experience before you start, but it's not worth 5grand. As ep said, do some study before hand and get a couple of trips in with someone whose qualified if you can.
However, if you have money to burn......
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I'm on my way!