Like Scott suggests, you can use a rapid setting thinset for the areas you expect to *need* to walk on and bridge it all with plywood or CBU (something to distribute your weight. I wouldn't set the whole floor with rapid set as it's a bear to keep up with, especially for a novice.
The danger of walking on your tile prematurely is that you may adversely affect the bond to the tile, causing failure down the road.
Relax and go out to dinner if you are able and wait till the next day to walk on the floor.
Remember not to walk on it wearing high-heels until after it's grouted.