Blood Test for Iqama

Al salaam alaykum!

I'm a 32-year-old American and arrived to Riyadh a few days ago on a one-year teaching contract.  I went through all the requisite medical tests back in the states in order to get the work visa, but I understand that I will have to have another check-up along with more labwork done in order to get my iquama.  The labwork would of course partially be to determine if one has used any illicit drugs recently, in which case the iquama would be denied.

Today is the 29th of August.  Though I am not a regular marijuana smoker I indulged for an instant on the 23rd, a few days before mobilizing to KSA.  It was two puffs from a joint which was also laced with tabacco- not strong. 

My understanding is that several factors help determine for how long THC stays in your system- if you're a regular smoker or not, your build and state of health, etc... It had been at least a year since I last had marijuana in my system, and I'm in good shape with a low body fat ratio.  From what I've read, it seems that it would take up to two weeks maximum for the THC to leave my system.

I need to wait until the THC leaves my system before doing the tests for the iquama, but I want to have the iquama before the 10-day holiday that begins on 30 September so that I can leave KSA for vacation. 

Does anyone have any idea how long it will take for the THC to leave my system or know how exact or extensive the tests are?  How long will it take to complete the medical tests and then receive the iquama?  Can I do all of this in a month? 

Thanks, John