It's more important to be consistent than to be early. If you want to wake up earlier than you do nowadays, but you are not currently consistent with your wake-up times, consistency comes first.
The two main aspects of consistency are: 1) forming a habit; and 2) nurturing a stable circadian rhythm. The two are linked, and investing in one will help with the other. For habit formation, we need to train our brains. For sleep health, we need preventative care for our bodies.
Sleep schedule consistency can be divided into two goals: getting out of bed at the planned time and being disciplined with bedtime. Making progress on both simultaneously is the ideal, but the first one is the most important so focus on that at first. As long as wake-up time is consistent, your body should begin anticipating and demanding bedtime naturally.
The main goal here is to achieve end-to-end reliability of the "waking up" routine, from alarm to whatever defines the start of your day. In practice, reliability means 1) to never miss the alarm, 2) to get out of bed immediately, and 3) to go on and do whatever comes next. Each of these can be a challenge requiring different solutions.
The good news is that this is easily solved with technology. The simplest method of not missing an alarm is to have one be astoundingly scandalous, such that it will wake even the neighbours if you don't silence it immediately. Not a song, but a loud and irritating machine noise.
If you're not a heavy sleeper, milder alarms should suffice. It's a matter of trial and error to find the minimally intrusive alarm that is maximally effective. After the habit starts kicking in and waking up feels natural and effortless, you can always revisit your choice to tone it down.
Haptic alarms from smartwatches are a good silent option. Using "sunrise" lights is also a nice trick: increasing the bedroom brightness slowly helps your body interpret this as dawn. Sunrise alarm clocks should help ward off drowsiness and might be slightly less disruptive to others when compared to a siren.
The best of both worlds is stacking alarms, so that most days you wake up with a gentle signal - but in case that one fails, a trusty and punitive alarm will make you jump out of bed. Ideally, set up the pair in a way such that when you actually get out of bed with just the first alarm, the second alarm is automatically disabled. Carrots work better than sticks, but we use both to seal the deal.
The major risk here is that your brain starts to learn how to perform the movements required to stop the alarm while half-asleep, so alarms that are too easy to disable might be disabled by your sleeping self and you might not even remember doing it. That's why getting out of bed immediately and without fail is the crucial next step.
Getting out of bed is easiest done if integrated with a particular choice of "backup alarm" - the one that fires if the first one wasn't enough. The strategy is to set this up so the backup shouldn't be controllable until you're already up. This can be a bit tricky to configure, but it's doable with clever automation.
For example, if your primary alarm is a smartwatch, have your smartphone be the backup and your phone charger away from your bed, maybe not even in the bedroom. Or if your smartphone is your primary alarm, create an automation so that after the alarm rings, the phone keeps sending you notifications every minute until it detects the living room lights are on.
The more complicated you make it to disable the backup alarm, the better protected you are from sleepwalking back into bed. Even better if that complication comes from whatever your first morning task is. For example, if your first order of business is washing your face, your backup alarm could be disabled by some automation that detects you've turned on the bathroom lights and they stay on for at least 1 minute but no more than 10 minutes.
Having a consistent first-thing-in-the-morning task that can be "detected" makes the setup easier, but it's also important to keep that task simple and rewarding. A warm shower or a refreshing face wash; making coffee or eating some fruit; something that's a bit like a simple everyday chore but still brings some concrete satisfaction in finishing it.
A good kind of first-thing-in-the-morning habit is the mechanical kind, something easily done while half asleep and without thinking. A few classic possibilities: taking a shower, basic skin care, eating a bowl of cereal.
It's not that doing things without thinking is great for you - it's not, even mundane tasks are best done with attention - but becoming a reliable drone comes before becoming a disciplined monk. One small task to kick off the day is enough to get started, though you can start appending more steps later on.
I use my iPhone Alarm app, and if I have my Apple Watch on (which I do for sleep tracking), the phone will stay silent and use just watch haptics as alarm. The alarm can't be snoozed. Stopping the alarm triggers a Shortcuts automation. This automation will send a notification every 45 seconds until I connect one of my audio devices to the phone (like my AirPods). These notifications are a pulse of haptics on my wrist that doesn't let me just sleep in peace after the alarm goes off. If I remove the watch, the notifications start to make sounds on the phone. The only way to fight this system in order to keep sleeping is to get out of bed and turn off the phone. The phone spends the night in a charging station far enough from my bed that I never turned it off without being awake enough to understand what I'm doing.
My system is not absolutely effective. I can get up, turn off the phone, and decide to go back to bed. The key part is that this is a decision, not something that happens without me having some consciousness of what's happening. The goal of this setup is to make sure I wake up. Given I did wake up, if I end up going back to bed that's a separate problem, with a separate solution.
The system is slightly overcomplicated because I like to wake up slighly earlier than my partner, so I prefer using haptics to not be too disruptive with her sleep. Without that concern, this is not too diferent from just having an alarm that requires you to walk out of your room to disable it.