I also used to stay up later and sleep later. Earlier this year I changed to a much earlier schedule. I didn't really have a strategy, just a process.

First, I decided I wanted to get up earlier and be more productive. From experience I know I need ~7 or so hours of sleep, and I want to get up between 5-6am. That means in bed no later than 10pm.

Next, set an alarm and get up. That part is simple.

IMO, working out first thing is one of the key components. I go to a gym now, but am buying things like kettlebells to do quick workouts at the house.

Finally, do it every single day. It's going to be hard if every weekend you keep sleeping until noon. This means on Saturday and Sunday, get up early and workout. I also have a social life and do adjust with life events. If I have something going on and am up until midnight on Friday night, I will set the alarm for 7am.

I should also note that I have mostly stopped drinking alcohol.

The hardest part to change was the habit of staying up late just wasting time on my phone, watching TV, or playing video games. For me it was mostly non-productive time. Even if I was productive, it was only partially productive because I had already been up all day.

Now I crave that super productive time early in the morning after working out. I'm wide awake, with no interruptions, ready to go.

There is also a bit of a psychological trick to beat procrastination baked in here. I wouldn't get up at 5am to play a video game or otherwise waste time. I pushed away from a comfortable pillow this morning, so I should make it worthwhile.

The biggest one was simply going to bed earlier. Every 3 days, I shifted my bed time by one hour. Within two weeks, I was going to bed by 11PM.

The hard part is telling yourself that you won't do any work past bed time. You have to have a hard red line. Takes a bit of discipline but it's just about 2 weeks of effort before you switch to a new habit