I typically have my Lean & Green for dinner, although sometimes I switch it up and have it in the afternoon. For me, I very much prefer having it for dinner. It gives me something nice to look forward to...the cooking and preparation, sitting down and eating slowly and truly enjoying it, everything about it. If I have it in the afternoon, I feel restless and bored in the evening.
My suggestion, is maybe try it for lunch and then see how you feel. You may find that you like it better in the afternoon, and you may find you prefer it for dinner. The beauty about the 5/1 is our ability to customize it for what feels and works best for our bodies and our lifestyles. It certainly won't hurt you to try it in the afternoon and go from there.