It took about 1-2 months before I was back to the same speed as I was on a non-ortho. The best thing I found to train myself was keybr.com, as it dynamically adapts to help train the keys you are worst at. And while learning it I didn't use any other keyboards, I just suffered through the process and it worked out eventually. The main problem after getting used to it was going back to any non-ortho, like on my laptop. So usually I just lug the keyboard and trackball with me whenever I travel.
Forgot to mention I swapped all the switches with Zealio V2 78g and lubed them. It's an absolute dream to type on.
Also, since that photo was taken, I've since moved the trackball between the halves, and keep them about shoulder distance apart. Really seems to reduce any kind of fatigue I had previously experienced working long hours.