I loaded up into AMR but it shows no changes but if I'm not mistaken I thought I read that it was best to get to around 40ish % haste and then go all into mastery. Thoughts on what to gem now? Thanks for any help!
Reason why AMR tells you there's no changes is that the default build will keep going for haste. What you can do is go to "Edit Weights" -> Haste softcap around 17100 just to make sure you're slightly above 40% haste, then once it does its haste softcap, it'll start pumping more mastery.
That or you can replace str+haste gems into str+mastery / exp+haste to exp+mast.