I am also struggling with the estimated times. I would love to know how to improve them.
I used this model: https://www.tinkercad.com/things/g2wf4flqvjs-anycubic-i3-mega-dial-indicator-mount
Which resulted in this G-code: https://gist.github.com/brnl/af0fc099c0c81589a79fd732e9f4bf9d
My printer is an Anycubic i3 Mega, and I have added it as a "Prusa i3", Gcode flavor 'RepRap'.
Hope this helps, and I hope you will be able to help me :-)