Stringing poly is sooo hard on my fingers. I used to have to bandage them up, after having trouble with slits, tears, and sawing through the skin. Then I found a pair of soccer (American football) goalie gloves that I use, especially on shaped poly strings. Comparing to synthetic gut (especially Spiral Flex) the sg is pliable, weaves very easily, and doesn't hurt my fingers.
But if you want to use poly, I'd jump right in and learn through experience. If you have a less valuable frame, I'd practice with that one. Also, what's great for practice is an inexpensive reel of Forten Nylon. But I found that the black color bleeds onto my clamps and gripper and I had to clean the machine every time. Get natural.