Real simple. You need to learn to crawl before you run. God forbid, get your CFI and teach some Private students for a bit, so that you can actually learn how to teach (which is what we are talking about.. not just "doing time" as an instructor). Then get your CFII. and take your teaching to the next level. Down the road, when you know what the heck you are doing, get the MEI. That way, you can take your teaching to the next level. And be able to do it well. Don't rush it, and don't look for an "easier" or "shorter" route to get things done.
Sorry, not directed at you specifically. But I get tired of reading people talking about the easiest route to take. Take the route that you will actually learn.. called the traditional route.
At our flight school, you can't even begin to think about getting an MEI, let alone teach in our Multi, unless you have been with us for almost 3 years and the owner and chief pilot give you the nod. Right of passage. And a few years and a few thousand hours of teaching under your belt.