Tiling floor in porch and entry hall
12 hours over night will be sufficient to get it set most of the way. You could Cut a piece of 3/4 plywood to fit the space ( one piece is better but two would work ) and lay it down over the tiles for the morning traffic.

The wood will spread/distribute the weight out over a broader area and should help to avoid a corner of the tile from being push down by concentrated weight. 

Just an idea.