There is one point that seems to have been ignored. Eventhough the bank will try to square off your open positions starting at 2.55 pm, in case this does not happen due to any reason, you will have to come up with the funds for your purchase.
Also, if you allocate Rs.3000, you can make trades worth approximately Rs.60,000, but the risk of losing your investment is very high. Taking the same example given by Siva, if you buy ASHLEY @ Rs.33 with a trigger price of Rs.32, it means that the bank will square off your trade if the price falls below Rs.32. Therefore, you will stand to lose Rs. 1,000 or more. A better way would be to set your trigger price to the lowest price of the day in the last 90 mins.
Should the stock move in your favour, then it will be a good idea to put trailing stops to preserve profits. For example, you buy 1000 shares of ASHLEY @ Rs.33. If the price goes up beyond Rs. 34, then you can modify your trigger price to Rs.34, thereby preserving a gain of Rs. 1000.
Hope this is helpful