In the entity mods for gobbos and such, there exists a line with two variables, 1 and 2. They answer the prompt for [WEALTH_TRIGGER:] or such. I do beleive, changing it to 1 would make goblins attack earlier.
Not exactly.
There's three lines:
[PROGRESS_TRIGGER_POPULATION:2]
[PROGRESS_TRIGGER_PRODUCTION:2]
[PROGRESS_TRIGGER_TRADE:2]
As I recall, that means that they won't siege or trade until you're of fortress level 2 (80 dwarves)
Setting them to 0 should make them siege immediately.
Having tried this, setting it to 0 turns it off. I have it set to 1, which helps marginally...
With any luck, the Army Arc improvements for next release (here's hoping) will ramp up the military game we all so bloodthirstily crave.