You will know when it's getting new roots. It will look like a small bump growing on the stem. I have a Phal growing a very new root, I'll take a pic of it and post it for you when my lights come on.
Phals are pretty tough. This one is my first Phal. It looks awful. Wasn't getting enough light, got overwatered, took me a while to figure out what it wanted. It's actually kind of touchy compared to the others. Wants more light, less water and more air flow in the pot. I had to make a pot for it. Standard slotted pots don't have enough holes. Now, finally, the darned thing is growing. I doubt I will see blooms from it this year though.