This is the program that would knock off a lot of time if he did it right -
https://www.bop.gov/inmates/custody_and_care/substance_abuse_treatment.jsp .
Lawyer's break down of how much it could reduce a sentence -
Completion Incentives
Completion incentives include early release under 18 U.S.C. § 3621(e) as well as consideration for maximum time in a prerelease community-based treatment program to include home confinement. For low and medium security inmates who may be in RDAP institutions far from home and have more time remaining on their terms before prerelease placement in a Residential Re-entry Center, another completion incentive is consideration for transfer closer to their homes. This is significant because the new policy clearly provides that an offender can be sent to any suitable institution for RDAP without regard for where the offender’s home is, based on program space availability.
Early release under 18 U.S.C. § 3621(e) for successful completion of RDAP remains the biggest incentive, of course, but has been significantly changed by Program Statement (P.S.) 5331-02. Whereas offenders who previously completed RDAP and were otherwise eligible for early release were eligible for a sentence reduction of up to 12 months, this new policy substantially reduces the eligibility timeframe for some offenders. Specifically, only those eligible inmates serving 37 months or more will now be eligible for up to a 12- month early release. Offenders serving 31-36 months will be eligible for only up to a nine-month sentence reduction, and those serving less than 31 months will be eligible for no more than a six-month sentence reduction.
The authority in determining some eligibility factors for early release (for example, whether prior offenses or the current offense might preclude early release) has shifted from the BOP institutions and regional offices to the Designation and Sentence Computation Center (DSCC) in Texas. It is noteworthy that, for the first time, certain sex offenders (those convicted of receipt and/or possession of child pornography) are not automatically disqualified from early release eligibility.