It is best to combine your s/r levels with some oscillator/momentum indicator. This way you can project some levels to watch and then when you get close to your targets you can use oscillators to time your exits more precisely. Time should rarely be a factor of how long you keep a position unless it was a variable when you started the trade e.g. report is coming out in 3 days and you know moves will occur soon after so you can time stop your trade in 96h for example. If the pattern doesn't materialize in predicetd time then order is not executed and you move on. Other than that, only the price action should dictate what you do.
I see the point and it's very important to have this kind of setups when you are working with your trades. Knowing when to place your entry and
exiting in your target time. Good thing with this, if nothing happens you can proceed and move on to your next trades.
Preparation and expectation both can be assess once you are already dealing with this market, use your knowledge and understanding to acquire success.