Hya Dennis! That's me you probably mean... ;-) After whole body cryotherapy helped me, a friend suggested Wim Hof's breathing and cold showering half a year ago, and I've been doing it since then, because it helps me a lot. I haven't read the book, just his website, delved a bit into his background. I use the breath-holding exercise (youtube guided tutorial, 3 rounds with 30 breaths, up to 90 seconds and more breath-holding), esp. when I'm flaring most. I've looked for similar breathing-exercises, seeing as it's developed from Tibetan sources, but nothing I've found/tried (and I've always done breathing exercises) works as well.
The cold showers do more than refresh, they numb the pain, carry off any inflammatory substances (so sez my rehab-psychiatrist). They even bring me down again when I'm awake and thinking at night, so I can sleep, very surprising to discover that.
You say you're starting with cool ones to get used to them. I'd suggest to increase the length after a warm shower, if it's that hard for you. One minute hot/warm, 10 seconds, 20 seconds, 30 seconds cold. In any case always start with your legs first, just 2 seconds per leg, 4x. When you've got used to that the same for the arms, then front. Last of all, head and back. I only do it short anyway, under 2 minutes. Usually 30 seconds, then soap where necessary (dry skin, so as little as poss.), then 30 to 60 seconds till I've got the soap off. If I fear my feet are too cold after (Raynaud): warm water on the feet, if I realize that after - hot water bottle. I'd love to hear how you fare with it! (Someone at last .... ;-).)