Oh, I don't recall when it was that I got my first sale, but I think it was past the three week mark. But, if it makes you feel any better I haven't had a sale in over two months, so...
Keep working on your shop. Do things like improve your pictures (although many are already great) and play with your descriptions, use all your tags. Do some searching on the blog to find some things to improve your shop. Also, you say all these really cool things that you do, but you aren't avertising that aspect of them on your shop very well. I know how nice the breaks in paragraphs in the shop annoucement are, but I can't see most of your promotional things, and I rarely click on those things.
Just keep at it and wait, it will come.