I'm nearing the end of my first dry start myself and my hc took about a week and a half of looking very similar to get rooted. Since then it's been spreading like wildfire and almost all the yellowing has stopped. Sounds like your off to a good start. My tank currently has a 13 hour photo period and I uncover and mist about every other day. Be careful on how much you mist. I over misted in the begining and wasnt allowing the tank to vent enough .ended up having to replace a few plugs of hc after the first week due to mold.