I've had an exfoliating eczema on my right thumb for years that sometimes would get so bad that the skin would crack and bleed and swell and was so sore it was useless for about a week at a time. I started doing gelatinous bone broth a little over a month ago and for the first time in years the skin on that thumb is clear and smooth.
I read Ray Peat on gelatin too (linked from Seth Roberts). Even though Peat seemed a little nutty, I tried gelatin for sleeping and found that it worked just like he suggested. When I can't sleep, I mix about one tablespoon of gelatin powder (from Amazon) with hummus or squash soup right before going to bed. The first time I did it I woke up under the impression that my fiance had forgotten to turn the light off. But no light was on; the sun was rising, and I had slept so soundly that I didn't realize that 8 hours had passed.
Yes, I supplement with gelatin i.e. I eat bone broths once a week. Changes? Over the course of a couple of years my nails are stronger and more supple and I recover from exercise and illness faster. My skin is in great condition. I would say you may need to wait a little longer than 2 days to see any difference, though.