In that case is it advisable to close trade at 10-20% profits or wait for target of 50%???
Close the trade as per your system/rules.
But just make sure to close the trade else you will end up paying STT unnecessarily.
STT on normal option trades done on the exchange is 0.017% of the selling side of the premium value.
STT on BUY option positions that get exercised is 0.125% of the entire CONTRACT VALUE. - Here contract value refers to the Nifty SPOT and not just the premium of the options.
So to understand this better - say you buy Nifty 8400 CE at 25 rs and Nifty closes at 8455 - you will end paying 8455 * 0.125% = 10.56 Rs
(i.e 10.56 * 25 = 264 rs per lot as STT.)
So profit = 30 points but STT 10.56.
But had you closed the trade before STT wont be applicable.
Hope this is clear.