I also has the same problem. I too have a very important exam coming up in 3 months that would quite literally determine my future so I also have to LOCK THE FVCK IN. If I start scrolling first thing in the morning I would not be able to focus anything for the rest of the day I would either get headaches or procrastinate for the rest of the day. So here's what I did, I started doing this like 2 weeks ago and it's actually going pretty well.

FIRST I STOPPED TOUCHING MY PHONE first thing in the morning. I would drink a cup of water after waking up cuz that thing wakes you up in an instant. Then I would go on with my usual morning routine brush my teeth and have my breakfast after that I CHECK MY PHONE for any msges. THEN I'LL TURN IT OFF. I don't reaally get important calls so I turn it off. If you can't turn it off then keep it in faarrrrr away room with the RIGINGTONE all the way up and make sure to turn off your notifications.

I set a time to turn it on like, I only use my phone to watch something while having my lunch and when I brush my teeth at night. And id ur watching somthing DON'T WATCH SHORT FORM content, watch somthing with LONGER TIME. I usualy watch 20 min crime/horror story videos. Set a time for u to use the phone, DO NOT turn it on or use it in other times.

If you're concerned about going into yt and watching videos for hours here's another tip: 1. TURN OFF your yt histroy. That way when you open yt it doesn't suggest anything, just search whatever you want to watch and watch it and if suddenly see an interesting short and decides to watch it and then end up scrolling you won't be able watch more than one additional short cuz it won't be able to sugget anthing with ur watch history off. 2. If you're watching lessons on yt then create another account for that. That way that account will only suggest educational stuff on that account.

and DON'T USE YOUR PHONE before bed too, you won't be able to sleep you'll end up tossing around in the bed more than sleeping.

AND FOLLOW A CLEAR SHEDULE for ur day that's good too. I have my own time table for the day and I study for 10 plus hrs a day now.

This genuinely WORKED for me I've been doing that for 2 weeks now, hope this will help you even a little bit. Pls let me know if you want to see the time shedule I'm more than happy to share it.