Enjoy the ride! Depending on how afraid of change they are, switching from Map to Pro can actually be fairly easy. I embrace change and look forward to trying new things so, after watching the intro courses on my esri training I was able to be up and running (wobbly but running J) in about a week or two. The hardest part is learning some of the new terminology (i.e.: panes vs views, atlas vs data driven, etc…). If you use in-house training from ESRI that time may be shortened a bit. My users in RPS are not quite as gung-ho as I am but with an in-person training session from ESRI they are able to wobble around in there, although they are still getting used to it. It’s slow though. Could be because their training had more to do with parcel fabric then arcpro usage though. I assigned them the intro training for ArcGIS Pro but short staff needs didn’t allow them to tackle it beforehand.

My best suggestion, make sure to do the transition during a slower period for your end users. Because of circumstance we were forced into a time crunch to get it done before taxable status season and it’s been a bit harder for all of us because of it.