Will it take 8 weeks to unlock the BR?
Each map/mode will load with a default, appropriate loadout. An example:
BIG MAP WITH LONG SIGHTLINES (imagine Blood Gulch)
- Frag Nades
- Map appropriate Armor Ability
Now it may take you a while to end up with precisely the combo you want, but the maps and modes are all carefully paired with VERY useful default loadouts so you don't end up on a giant map with nothing but an AR and a sadface.