I've been cutting into my bread as soon as it comes out of the oven. Hot! with butter! Yum!
However, I recently read that it was wrong to cut the bread so early. It should be left to cool, as the residual heat inside the loaf finishes cooking the bread. If you cut the bread, you let out the heat.
I've managed to hold off on my last two batches of bread (once until the bread was completely cool, once until it was still a little warm but ...). I think the bread does come out lighter if I wait. Plus the bread knife doesn't get gummy.