how soon would a mro call usually?

I have been clean for 21 days exactly on the test date. I was taking alot of detox pills and consuming approx 90+oz of water a day up until the test morning starting about 1 week before test date. The morning of the test i consumed approx 4pt of water before the test and the urine was the number 4 pee of the day. I was not a heavy smoker a 1/4 could last me a month but i did smoke every day at night a couple tokes and the weekend blaze all day. I am 5'11" 225 i eat junk food alot and don't work out so i would assume i don't have that weak of a metabolism but its not the fastest either i would think average to a bit above average since i have been 225 for like 3 or 4 years now.

I have received no call from the employer or a MRO asking questions but i was clearly told the results would be available within 48hrs more then likely 24 hrs. we are on day 4 no calls and i am a fucking wreck big time on the stress right now. Would a MRO call before they do the second test or would they normally call after they did the second test and then ask questions? The company in question is firestone/bridgestone and considering there more or less the godfather of creating this drug testing mess were in with that report they wrote way back when i am pretty worried.

I did take two "At home Drug test" and yes there was a line it was so so faint i thought i might be imagining it but my wife confirmed it too although she said she could be imagining it too. There was ever so slight color to it so not one of those pasty white ghost lines but still really really faint.

My concern is of course is testing below the 50ng mark and not having heard anything and i am supposed to be starting in 3 days concerns me.

Sorry for the ramble....

Thanks for the insight any one can provide on how the MRO happens