We have a household of "not a morning person".
We also use the timer for everything. I would recommend going with a Time Timer instead of a digital, because I know my kids have a hard time with the concept of time passing, and the Time Timer is more visual. Downside is the Time Timer is more expensive and more fun to play with.
The way we work things here, and not saying we're Perfect Parents,

but if the kids are up, dressed, meds, breakfast, whatever time is left they can play Wii or play on the computer. This is a pretty effective bribe. I will admit at first I was waking them up 15 minutes earlier than usual, to guarantee some play-time. Your kid might not care if he gets to play on the computer, but at our house it's major currency.
The other thing I've found effective with our oldest, is telling him point-blank: "We leave the house at 8 a.m. If you're still in your pajamas, that's how you're going to school. If you haven't eaten, you'll just have to starve. If your teeth are nasty and you smell, that's too bad." (I don't mention vitamins or meds 'cause those aren't negotiable) He hasn't called my bluff on it, but I
would take him to school in pajamas, because it would only happen once.
Last spring I was sitting in the school office, I had come to pick up one of the DS's for a dr appt, it was about 10:00. A mom came in with her son, checking him in, told the secretary that she couldn't get him out of bed in the mornings and could the counselor talk to him?

I had no idea that parents did that. Honestly.
And like bookworme pointed out, if your son is on a stimulant for the ADHD, that could be really messing with his sleep. We had that problem, too. We've switched meds but now I don't think this one is working, so I don't have an answer for you there. But DS got in a nasty pattern that way-- the stimulant interfered with his sleep. So in the morning he was groggy because he didn't get enough sleep, then it was time to pop another stimulant, which would wake him up and get him hopping for the day. And that night he'd have trouble falling asleep again. And yes we tried melatonin. And the next morning he'd take his ADHD meds to get woken up again. That's not a good cycle. I don't know exactly how to fix it, either.