Late to school - breaking the bad habit

[aLittleL1fe]

My 17y old gets up / sets off late every day since September. He is either late or nearly so most days and never even a single second early. A few times school rang to ask where he is because he also forgot to sign in (when he was already late and rushing). I suspect possible ADHD (not just because of this but for many different reasons). I think he agrees it's important to be on time, he doesn't feel that it should be hard but when it comes to actually doing it - nothing changes. He ignores his alarms, timers etc in the morning. I am currently able to 'help' him by giving him a lift but this will have to stop in a month when I'll have a new job and I will no longer be able to do it. With ADHD in mind, and also his age (young adult) what would you advise? I'm asking him to come up with a plan to improve/change things but we're not getting anywhere.

Mine was similar - used to go in a wake him, remove duvet and open the curtains. Then yell up the stairs at regular intervals. He was still technically a child, and I was the parent. I saw it as part of my job to get him to school on time. He was given several detentions for being late, and that had no effect at all.

He is at uni now and makes his lectures on time, so they do grow up eventually.

Very loud alarm at the opposite side of the room he has to get up to switch off.

If he doesn't leave on time set it earlier until he does.

If he is ignoring because he feels tired he needs to go to bed earlier.

Difficult to enforce though unless he wants to change too, as at 17 he should be starting to be more independent and making good choices (such as getting up!) rather than needing more prompts.

Mine was like this too, but as @Seeline mine is also at uni now and up early and never misses a thing (he lives at home so I know this is true)