Hello aspirant

Class 10th is the time when you decide your stream. Focus on your board exam so that you get the stream of your choice.

In class 11th when you get PCB or PCMB then you can start your preparation for medical colleges.

All the best

Focus on your Board Exams first. The best time to start preparing for medical entrance examinations (NEET UG/AIIMS UG/JIPER UG) is from 11th Std.
However one thing, make sure whatever Physics, Chemistry and Biology (Science) you will study or studying now in 10th Std, must be thoroughly clear and you must have a clear cut concept of each chapters.

Thank You
Best Of Luck