when you buy two lots, one to close your short and one to go long. than your net position will be one lot LONG and not two lots. now if same day, market trades below support, than you have to sell two lots. one to exit long & another one to enter short. so again your position will be of one lot SHORT. There is no need to wait for 5 minutes. Insted either wait for 2-3 minutes or pointwise, wait for say 7 to 10 points and whichever occur first, change your positions. Usually i place my stoploss orders everyday after market settles, below/above 7 points of doubly qty to change my positions automatically so in any case due to technological problems like connectivity or electricity problems etc, atleast my positions gets changed in time.
Vinod