Mitigating prior drug use for DOE Q clearance

I accepted an offer for a position that requires DOE Q clearance to be attained within 24 months of starting. I need to submit my e-QIP this week or the offer will be rescinded.

I have no arrests, financial difficulties or other issues that I believe could be potentially disqualifying.

6 years and 10 months ago, when I was 24, I went to a music festival. I purchased LSD for myself and others (not for profit) and brought that with. Additionally, while I was there, I used acid, MDMA and one line of cocaine.

That is the only instance of illegal drug use within the 7 year window. I was 24 at the time and it was less that one year after graduating college, while I was still living in the college town with college roommates.

Shortly after, I moved to a different town and stopped associating with people I had used illegal drugs with. About 6 months later, I moved to a different state where I have been gainfully employed for the last 6 years, got married and had children.

Is there anything I should do on my e-QIP to attempt to mitigate the prior drug use or should I wait until my interview? Given the details above, do I have any chance at interim clearance? What are my chances for DOE Q approval?