Need information regarding hair-testing and Northrop Grumman (shipbuilding)

Okay, first timer here, and I have two questions:

1.) How far does the hair follicle test go back with Northrop Grumman? Couldn't seem to find an answer for this anywhere on the internet.

2.) Didn't smoke marijuana for about a year, and I took 3-4 puffs two days ago and haven't smoked since. Used to smoke cigarettes but I'm quitting that for good, along with alcoholic drinks (I rarely even drink, only once in a blue moon). Also sworn off coffee and green tea until after such a test. How long do you guys think it'll be before my hair would be clean enough for me to consider applying for a job at NG and taking the follicle test (without using special shampoos and home remedies)?

I'm not in a hurry to apply right now, but some information would be really helpful. After all, knowing is half the battle! Thanks in advance!