Well, assuming that you care for the TV (even after six months use)and you'll repack it into the box it came in for your journey, and then you will have to prove that it is actually six months old (and therefore used)to Customs in India.
The only way you can do this is with the original receipt.
So, you can either buy the TV, keep it in its box for six months and then travel with it (saying that you have used it) or just buy the equivalent TV in India and save yourself all this hassle.
If you produce the receipt to Customs in India (proving that date it was bought) then this will also reveal the TV's value and they may still hit you for tax anyway.
Well, assuming that you care for the TV (even after six months use)and you'll repack it into the box it came in for your journey, and then you will have to prove that it is actually six months old (and therefore used)to Customs in India.
The only way you can do this is with the original receipt.
So, you can either buy the TV, keep it in its box for six months and then travel with it (saying that you have used it) or just buy the equivalent TV in India and save yourself all this hassle.
If you produce the receipt to Customs in India (proving that date it was bought) then this will also reveal the TV's value and they may still hit you for tax anyway.
Seems like a lot of trouble, and risk.