
How much overall experience is required to C3 - A grade
How much overall experience is required for a C2 grade employee to move into C3 - A grade and does it require anything like he has to stay in tcs for this many years to move to C3 grade

C2 at 4years of exp. C3A at 8 years of exp. But this is just an assumption there is nothing written. Everything is in the hands of the project manager, your reputation with manager, your unit. If they want they can do it early as well.
As of now now promotions are happening so not sure when it will happen

Ideally, you will be eligible for promotion after 3 years from the last promotion.
So, potentially at 7+ years one will be eligible for C3A if he received ITA in his 4th year.
C3A promotions are considered half yearly, so again there can be a delay with respect to the month of year. There can be fresh guidelines for each quarter from time to time.
like no D band in the last 3 years, A/B in last 2 consecutive years, minimum 4.5 years in C2, etc, count of promotions allowed in the account as per account margin. On top of this, your manager should be ready to give you promotion during the promotion cycle.
Promotions are on hold nowadays, and promotion eventually reduces the monthly salary considering the dip in QVA even though CTC is more

I joined tcs at c2 grade with 6.5 yr experience... I got good feedback from customer and created dependency which helped me for my promotion in just 1.5 yr of experience inside the team

I am C3A if you are lateral hire, it is 7 years and above and depends on you salary (15-20 lpa) if you are in tcs for langer period of time then it will be 8-9 years of exp

7 Years plus

I joined TCS in C3A band and that time my experience was 7.5 years