Giving a minimum time is not possible, because it depends on the size of the loaf, whether it is in a pan or not, and the ambient temperature of the location where it is cooling. In general, the recommendation is to cool the loaf to room temperature. If you are baking rolls, this might mean 30 minutes. For a larger loaf, it could be hours. At the risk of providing information captured in other questions...There is a process called starch retrogradation that takes place as the bread cools. This means that water absorbed by starches during the baking process is expelled at the molecular level, and evaporates. Cutting too soon means you risk a gummy textured bread. Next, cutting your bread too soon releases trapped steam, this could mean that your bread is drier, later. Finally, depending on the ingredients, flavor continues to develop as your bread cools. All of this is carefully explained here. I would also suggest that you don't want to shortcut this process. It takes a bit of effort to produce a good loaf at home. My guess is you've already planned ahead quite a bit. What you want is a loaf that has cooled to room temperature. Then you can heat it for your guests, as restaurants do.