Calibrate just before you disengage the AP, and don’t forget to use trim! Sometimes, a quite substantial amount of trim is needed. I occasionally use up to 40-50%.
Regarding the VR question, i bet you can find some useful information in this topic:
I usually rotate at around 140kt in the 737 with flaps set to either 10 or 15. Depending on weight.
(I’m nothing but a ordinary pilot in Infinite Flight like most here, so IRL might be a totally different story. Just telling you what works for me.)
I’ve used the chart before, but when I use those speeds with the flaps on the chart, I can’t lift off, even though I calibrated my device. Normally, I rotate at 140 with 10 degree flaps. Is that high or low?
Along with what Sebastian said, I suggest disabling the AP one at a time. I.e. disable the altitude lock first, then when that is under control disable the heading. Makes it one less thing to worry about.
And if you still aren’t sure about the vr speed, what I usually do when testing a new weight config is take it on a practice run in solo mode, and find the right balance.so I don’t crash on Expert and embarrass myself