You can do it however you like. I can't remember who wrote it, but there was some intersting data showing the benefits on a 2nd PWO shake 1 hr after the 1st.
Personally I'm a big fan of whole food meals, both pre and post-WO, although shakes do have uses. I would take my WMS immediately post-WO, and then have a solid meal 30-45 minutes after the WMS (Plus some protein, preferably hydrolysate or other fast digesting protein)