Count back from the exam date, split the material, and build in review and slack days: a planning method that holds up.
The main reason plans fail is not weak willpower but that the plan never matched reality in the first place. If you set the daily load based on your best day and leave out school events, plans with friends and sick days, you start falling behind within about three days. Once a plan slips it is hard to catch up, and eventually you abandon the timetable and study whatever is in front of you. A good plan is therefore not a tight plan but one you can get back on after it slips.
Start the plan from the exam date, not from today. Count the days left, then remove the days you genuinely cannot study. Next, set aside the last few days for going over everything again rather than learning anything new. When you divide the material across the remaining days, the daily load becomes a number. If that number is unreasonably large, it is a sign to adjust the scope or your goal before you go any further.
Write each day's plan as work to finish, such as "translate the unit 3 reading and check the vocabulary", rather than as time, such as "English for two hours". Time-based goals feel complete as soon as you have sat there long enough, and they tell you nothing about progress. Output-based goals are clearly finished or not, and they make the next day's task obvious. At first you will misjudge how long tasks take, so jot down the actual time next to each one for a few days; your next plan will be far more accurate.
A plan that lists only new material tends to end with you having forgotten the early chapters by exam week. What you learn fades quickly, so schedule short review slots a few days after the first session and again about a week later. These reviews do not need to be long: close the book, recall the key points, and check only where you got stuck. The memory techniques guide goes into how to space those reviews.
Every plan needs empty days. Leaving roughly one day a week unassigned lets you catch up on whatever slipped that week. If nothing slipped, use it to get ahead or to rest. Without slack, a single bad day pushes every later day back by one, and that pressure is what makes people give up on planning altogether. A plan that feels a little generous when you write it often turns out to be about right.
Giving every subject the same time looks fair but is not efficient, because subjects differ in how much material they cover, how strong you already are, and how much they count. Generally it raises your overall result more to give extra time to broad subjects where you are weak, and to keep strong subjects ticking over so you do not lose your touch. Subjects like maths, where it takes a while to warm up, work better as a little every day than as long occasional blocks.
A plan is not something you write once; you revise it every week. At the weekend, put that week's plan next to what you actually did. If the same subject always slips, you misjudged its daily load; if your evenings keep vanishing, something else is crowding into that time. Feed those differences into next week's plan, and within a few weeks you will have a plan that fits your real pace.
The most common mistake is spending too long decorating the timetable. Colouring and aligning boxes feels like studying, but no material gets covered. Another is rewriting the whole plan because one day went wrong. Absorb the backlog with slack days, and rebuild the plan only once, at the weekly review. Exam scope and dates do sometimes change, so keep checking notices from your school or the exam body.