When you are exploring what are the qualifications to become a pilot one of the key criteria is the total flying hours you must log and the timing of when you complete them is just as important as how many hours. Let's break it down in simple terms.
Flying hours include different kinds of flight experience solo flying (you alone in the aircraft) dual flying (with an instructor) cross-country flights (from one airport to another) night flying instrument flying (under poor visibility or using instruments alone) and being Pilot in Command (PIC). These hours show that you've had enough practical experience to operate aircraft safely.
You begin logging flying hours after (or concurrently with) ground training. First you attend the ground classes covering air regulations meteorology aircraft technicals navigation and communications. Once you clear the required ground exams, you proceed to flying training. According to the licence type:
For a PPL (Private Pilot License) you must complete about 40 flying hours in India (20 solo + 10 dual plus other flights).
For a CPL (Commercial Pilot License) you must complete around 200 hours (for aeroplanes) which includes specified PIC cross country and instrument hours.
For an ATPL (Airline Transport Pilot License) the highest level, you may need up to 1,500 hours depending on type of aircraft and role.
You cannot just accumulate hours willy nilly. The hours must be logged under conditions required by the regulatory authority (in India the Directorate General of Civil Aviation/DGCA). For example certain hours must be PIC certain hours cross country distance some at night or under instrument conditions. If you finish your ground training first and then start flying, you will meet the timeline efficiently. If you delay flying your licence progression may be delayed. Also flying early gives more time to master skills.