The precision starts with, how the systems analysis potential trades.
Before a trade can be taken place, there must be a signal.
The system differs between a open to buy signal and open to execute signal.
Before an actual trade execution can taken place, a buy a signal has to appear.
In practice, the system analysis in the back test window the data do a certain date.
If at this date, a signal is generated, the underlying security is then bought at the next trading day at the market open.
This is the most accurate and only method to find and test a trading system which then can work in real trading environment - and win.