Ok, seems there are some questions about the start of the economy.
So i tested over my last few fortresses. First one few, with each caravan that came in i traded lots of stuff.
This last one, all i ever traded away was stuff that didn't count towards my fortresses wealth, grey stuff that goblins and kobolds left behind. mostly narrow leather, as i melted the iron stuff.
Now, i have 10 artifacts, 2 were the kind that don't give you legendary dwarves, and two were from children, so i have 6 legendary crafters from those. Plus my mason is legendary just from normal work, and my stonecrafter as well.
So, needless to say, i have a heck of alot of wealth, alot more than i have in other fortresses that got their economy realy quickly.
Usually my economy starts fast, as i tend to pick heavily forrested areas and get a guy carving wooden crossbows right off the bat. And that's what i tend to trade with (cept elves, i trade stone crafts and other stone items with them)
So, my opinion is that trading wealth is what starts the economy. not accumulating wealth.
Course, i still haven't gotten the economy started yet.
I sent the last two (human and dwarven) caravans packing loaded with master bows and leather and stone goods.
I've already got a hoardmaster, not sure what that means though. And had two goblin invasions.