It really matters on your own cs abilities. Poor cs, which begs the question why you're AD carry, should probably max Q first (after W in all cases). E is really only noticeable with large cs scores on Ashe. It's not like GPs Q which stacks up hard and fast, or TFs passive which starts high all around and helps others. You could probably get away with 3 points into Q, then max E, finish Q as final 2 levels, as the slow increase is only like 5% per level. E isn't that noticeable in late game, where farming can't occur as easily, so you have to get it early for it to be noticable.