With proper artifact component management, by the end of year 2 a well-managed fortress should be passed 1 million Urist in wealth I would think. Certainly by the end of year 3.
If you dive for the magma sea and find some raw adamantine, you can easily hit 30-40 million by the end of year 5 or 6. (Adamantine or raw-adamantine based artifacts will be in the ballpark of 1-1.5 million by themselves. Buildable furniture double counts! Even without adamantine, selecting high value components for artifacts can be punching towards 1 million value routinely.)
And that's without trying to maximize wealth too hard. If I turned my forges on full blast and decorated the heck out of platinum and gold furniture and built it all, I could probably double or triple that trivially. Also, masterwork suits of steel armor for everyone in the fortress, it's a lot of dwarf bucks in value.
My 16 year fortress is at 75 million, at least 70% of which is artifacts, with much of the remainder made up of expensive furniture for nobles, the armor and weapons of my extensive military, and the several hundred masterwork serrated steel discs in traps. (And probably a couple million from total mechanism production...). (Consumed food and destroyed clothing don't count towards your fortress value). I haven't particularly been working my citizens hard or trying to maximize the wealth accumulation curve. I seem to recall having hit 30 million sometime around the year 5 mark, at which point the fortress was mostly delved, engravings were mostly done, and the megaproject I've been working on in fits and starts isn't actually worth all that much. (After year 5 I've mostly been letting it run in the background while doing other stuff).