You will want to seal the grout first, I presume. So you can't do that until 72 hours after the grout is set. The grout should have 2 coats of sealer. If you do that in the morning, by afternoon you can set the appliances in place.

It does not sound right that you wouldn't seal the grout. Maybe he meant the tile itself? AquaMix Sealer's Choice Gold is a recommended grout sealer - you can get it at Lowe's. I think you have to wait at least 24 hours to clean the floor -- you want the grout to cure. Did they clean the grout haze off of the tile? You will know if it's haze if it doesn't come off with plain water - try cleaning a few tiles with a wet terrycloth or microfiber towel, then let dry. If the haze returns, you'll need to clean that off. Ask at this forum for the safest way to get it off. They can also recommend a general cleaner. Personally, I just use a Bissell steam mop with no cleaner, just water. Works great and takes so much less effort than regular mopping.

Thank you all so much for your input. In all my research, and talking with some general contractors in Chicago, they told me absolute no-no and that it is incredibly unprofessional - they have never seen it done especially in mid and high rise cement construction buildings in downtown Chicago that have concrete floors. They explained that the red oak 2 1/4" solid wood floor is not secured to the concrete and that there is expansion/contraction/movement making it an unsuitable subfloor/ surface to directly lay tile down on top of because tile requires a stable surface. I can literally hear squeaking sounds like the floor is moving, because I hear squeaks when I walk on my own red oak original developer installed floor. My neighbor doesn't understand any of this or what the potential issues/implications are for us both and asked me to try and explain it to him. How would you explain this situation to them? Won't their tiles/grout crack and break and they will lose their floor? Should we both be worried about any structural/weight/load issues? @glennsfc, can you please help me understand using Schluter Ditra over securely fastened hardwood and why you suspect this was not done? Thanks and so appreciative!

I like stacked to keep things ismple and also matching grout for the same reason I sometimes do an aceent strip not centered on the long shower wall I do it vertical and use that same accnet tile for the backsplash for the vanity to adda bit of bling. I do the same pattern for both floor snad shower walls .