In real life they have auto brakes which deploy as soon as you touchdown. You can see this when you use APPR as well where it activates brakes by itself immediately after touchdown.
As for reverses, they are stowed at I believe 80 knots in real life because any slower than that would cause engine stalls or cause the engine to pick up debris.
So yeah, don’t use brakes before landing, that’s not realistic, apply them as soon as you touch down.
As for brakes from the rudder slider, these simulate the breaks which are applied when the pilot presses the top part of the rudder pedals to disengage auto brakes and allow for manual and differential breaking which you can also use when you drag down the rudder slider for rudder pedal breaks and left/right for differential braking during the final moments of landing roll.