How do Kalpit Veerwal prepare their timetable & stick to it?

He used to maintain a diary where He used to write down their time schedule for next day before going to sleep. If you have a problem in maintaining your timetable, then you can set reminders and alarms for it. As for revision of 11th I suggest this-

First of all never revise 11th at the cost of 12th. First you should do all your class 12 study with complete satisfaction and then take out some time daily around 1-2 hours to revise 11th. You may also utilise Sundays and holidays for this.

If you have an upcoming chapter which requires use of some 11th concept( like electrochemistry requires ionic equilibrium) then revise it first to understand the 12th topic nicely.

Then you should revise those topics which are basic and important like NLM, SHM,Rotation, Mole concept,GOC, Quadratic equations, Straight lines, Trigonometry, etc. which are to be used in 12th topics as well.

Topics like Binomial Theorem, Probability, Permutations and Combinations, Properties of Triangles, Fluid Mechanics, Elasticity, Hydrocarbons, Real gases, etc can be revised later as they don't have much use in 12th.

Some methods to save time are: study gravitation after electrostatics, study waves before wave optics, 11th chemistry atomic structure after 12th modern physics. Also study thermodynamics well as it is common to both physics and chemistry.

12th should be revised after 11th is done as 12th concepts would be new and more likely to be strong.

For time division, do fix slots of PCM each at regular intervals in a week so that you would have revised all subjects in a week.

All the best!