I start out with 4 builders (mining, masonry, architecture, mechanics, stone detailing), 1 farmer, 1 craftsdwarf, and 1 trader.
The builders dig out the fort and work stone help build the defenses. The farmer provides food and booze. The craftsdwarf builds beds, bins, barrels, and crafts of various kinds. The trader also works as my book keeper and manager. When there's no work to be done at the moment he functions as a very good hauler, being perfectly agile after working on the books for so long.
All work is done via immigrants, such as metal working and whatnot.
However, due to my not liking micromanagment, I assign immigrants into just a few "castes."
The craftsdwarves do all crafts as well as carpentry, crossbow making, and wood cutting. No need to bring axes at the very start, they can pick up axes as they're produced.
Farmers (+furnace operating) are the basic peons of the fortress. They collect herbs, plant, harvest, make booze, cook, do all the dirty work in the smelters, and haul on the off season. All peasants are given the farming jobs upon arrival.
Metal workers at the only dwarves that keep their specialized profession, since its often so difficult to get a legendary metal worker of any job. Also, I will only have 1 metal worker of each type, so a maximum of 4 per fort. The lesser skilled ones are sent into the military, allowing the single dwarf of each skill to max out their abilities.
The original 4 builders keep a monopoly on their professions. All immigrant masons, stone detailers, miners, and mechanics go into the military.