Hey now, I have those primos diapharagms, actually just got them a couple weeks back, they aren't a bad sounding call. Although I am now getting into some other options.
It has also been several years since I operated a turkey diaphragm, so I didn't have that experience to help me when learning these.
What I did: Keep the call in your mouth, all the time, I always kept it in my mouth, you can keep it off to the side to get it out of the way, then move it into position like you are going to use it.
The more you have it in, the faster your mouth will learn that it is a call and it doesn't need to water so severely, this also helps you to get the movements down for the field. You can keep a diaphragm in your mouth the whole time, you can operate your open reed calls and keep the diaphragm in your cheek, then when you need to stop a dog, BOBs your uncle.
I love the sonic dome, I already wore a hole in my double howler, that sonic seemed to be easier for me to learn on as well. Although that green dome actually had the roof of my mouth bleeding a bit early on, I practiced non stop for 2 or so days in a row when I first got them.
Now I can just pop them in and it is natural for me to use them and move them around in my mouth, a lot less excess spit.