How to get a decent military by end of year one?
1) Embark with 4 dwarves with 5 skill points in teacher* and 5 of dodge/dodge/armor/shield, 1 dwarf 5 armor+weaponsmith, other 2 as you will (e.g. farmer/brewer+leader/doctor)
2) Bring 4 picks, 10 coal, 10 copper, 10 cassetirite and 1 refined coke
3) During spring, let the 4 soldiers mine out needed quarters: farm, dining hall, bedrooms, crafting, smithy
4) ASAP, start smelting bronze and making weapons, helms, shields, armor
5) Also ASAP, but certainly by late spring / early summer, set the soldiers to train in two squads of two soldiers, make sure their squad is active. If you don't have 4 weapons yet, give them training weapons. I prefer giving them a mix of weapons since they will act as seeds for your squads.
6) fortress development will slow to a halt since 4 dwarfs are busy with military stuff and 1 or 2 with smelting and smithing. This will fix itself with the two migrant waves. Anyway, who needs a big fortress? You probably want someone crafting trade goods asap, but for the rest food and booze is all you really need.
7) By the end of year 1, they should be approaching elite level. When the first 'big' migrant wave comes in, split the original soldiers into 4 squads and assign recruits from the migrants, hopefully with some skill points in the weapon you are aiming at.
Also, try to recruit some marksdwarfs from the first wave, and get them practicing.
By the end of year 1, you have 4 highly trained dwarfs in bronze weaposn and armour. By the end of year 2, you should have 4 melee squads and 2 marksdwarf squads, also well trained and well equipped.
*) Sparring is better than instruction; however, they will do instruction sessions anyway so you might as well have decent teachers. I've not tried using teacher/student instead of teacher/defensive.