when can i tell yeast is active

DAve, It depends on the yeast you're using. I don't have any pics; its a bit different with each yeast you use and the temperature of the must. Montrachet yeast is very foamy, but other yeasts (like Cotes de Blanc yeast)I have used are not. I usually look for bubbles, a little foam, and I listen for that sound (bubbling, swishy noise) the must makes during the initial fermentation when everything is working. In fact, I usually listen now rather than look about 12 hours after I add the yeast. The other way to tell if your yeast is working is to test the SG to see if it is dropping. As I was rereading your post to see if I missed something, I noticed you hydrate your yeast and add it (which is good). I usually just sprinkle the yeast on top, but the yeast doesn't usually stay there. I've watched it hydrate and sink to the bottom, and then about 12 hours later you can see that its working. I would think that even when you hydrate your yeast prior to adding it to the must, you would still need to give it some time to get itself really going in its new environment. Darlene