No one here can give you a direct answer. Since you seem to be adamant on admitting to this use on the application, there is really nothing you can do but try and see what happens. Here's my story.
Flashback to 2010, I'm just graduating high school. I experimented with MJ use during high school as well, emphasis on experimented. I spent a semester in college and became interested in AFROTC. I went for my initial interview with the Det CC to go over things. I didn't say anything about the MJ, and he didn't ask. I called later because I was scared what might happen if I didn't say anything. He told me I was ineligible for ROTC. I was disappointed but understanding. I finished that year at college.
Flash forward six months. I had decided to pursue service and enlist in the USAF. My job required me to hold a Top Secret clearance w/ some extra secret squirrel stuff. The forms I had to fill out were ridiculous but I was perfectly honest about everything, full disclosure. My clearance was approved.
Within the first six months of my first duty assignment I was briefed on the USAFA and programs to commission enlisted personnel. I decided to apply and see what happened, full disclosure once again. Keep in mind that the process for enlisted personnel is nearly identical to civilians. I expected to be rejected in a similar fashion as AFROTC, but not I'm part of the USAFA Prep C/O '13
The bottom line is that "being of good moral character" is subjective. One service may think your offense meant nothing, while another service might throw your application/appointment out in a heartbeat. In my case, I think it was the fact that I was enlisted, held a TS clearance, and it had been a few years since the incident.
There's really nothing you can do but try.