Neighborhood Smoker

I am seeking employment in the near future and an seeking opinion's from those who have gone thru about the same situational factors.

Facts of the matter:
Age: 21
Height: 5 11'
Weight: 145-155
High metabalism - can't gain weight.

Smoking history:

September 2007 - Dec 12th 2007- During this time period I smoked about 1/2 oz - 1 oz per week. Mostly low potency Mids or what some would call dirt. During this time frame I took maybe 2 weeks off from smoking at most.

I abstained from Dec 13 - Jan 27th about.

I smoked from the end of Jan until May 7th. During this time I smoked about 4 oz's of lower potency marijuana and about 1 oz of high potencty.
I quit for a week during this time period and have been cutting down to about 1 shared blunt per day a couple weeks before quitting.

any estimates on when it would be a good idea to get a self test?