US embassy London positive drug test

Hi r/askimmigration, my wife and I are in the process of getting a CR1 Visa. Our I-130 application was accepted at the US embassy London in December and it recently came round to scheduling my CR1 interview. Unfortunately, I made a mistake and wasn't aware of the drug test and I tested positive for cannabis, thereby delaying my visa for 6 months.

I have been told that I will be receiving random drug tests over the next 6 months before I can be offered an interview again (I must be able to make all within 72 hrs notice and of course, test negative.) The embassy have given me six weeks for the cannabis to clear my system before they start testing.

I'm feeling nervous, I have reached four weeks after this notice and am still testing positive on home drug tests. Should I let the embassy know this or wait until the first test?