In any instance as you point out there always seems to be a "null" point during rotation and one nearly always ends up "blipping" some aft trim after T/O!
The term "Null" really does describe the sensation of the pause succinctly. Thanks for that and I will remember to use it during simulator briefings on engine failures during the take off phase.
During type rating and recurrent training (simulator of course), it is quite common to observe the pilot caught by surprise (despite being briefed earlier) at the heavy stick force needed to initially rotate on one engine and while dragging the control column back through to 10 degrees.
Often the aircraft will gently sink back on to the runway as they inadvertently relaxed the heavy back pressure during the one engine rotation instead of maintaining the back pressure through the "pause" period of a couple of seconds. Sometimes pilots will then use the stab trim to help with rotation forces.
That brings with it its own problems as we see pilots relying on the stab trim to "fly" the aircraft instead of using elevators to set the required attitude followed by stab trim to fine tune stick forces. It takes several of these manoeuvres (repositioning each time) until pilots are confident they can handle engine failure at V1 and continue to VR on one engine and climb away without momentarily allowing the wheels to hit the runway mid rotation.