I ferment my chick feed. If the multi flock you've bought is marked that it is ok for chicks 0 - 8 weeks old (and it should be around 20 - 22% protein, not 28% protein!) then it would be fine. Initially, for the first week, I buzz it in my blender to be sure the crumbles are small enough for the babies. But, if you're fermenting, that shouldn't be necessary. The best time to expose them to sod to boost their immune systems is during the first 2 weeks. I always wait until they're eating their regular feed well, (know where the feed dish is, use it well, and have full crops regularly). Then, I give them the sod. Be sure it's sod that has not been exposed to insecticides/herbicides, and that any grass is clipped short. If it doesn't have any grit sized particles in the soil, be sure to supply chick grit.