Dear issacj,
You need to trade as per trend, buy calls at S1 when Nifty is up 20pts at 10:30 AM from the opening price at 10:00AM and use trailing SL =10% from CMP and hold. If Nifty goes down by 20pts by 12:30PM w.r.t. price at 10:30 AM, then obviously the trailing SL of call bought at 10:30...