when bread is doubling, right before "proofing"
When the bread is doubling - that
is "proofing". Bread may be proofed once or twice - depends on the bread and the recipe. Unless you are going to store your dough in the refrigerator to "retard" the proofing - you don't need anything but a clean kitchen towel.
If you are going to proof twice - mix and kneed your dough, put into a greased bowl, turn it over so it's greased all over, then place a clean kitchen towel over the top of the bowl and allow it to proof the first time. After it has doubled in size, take the dough out, punch it down, form your loaves, either place in baking pans or on a baking sheet (depending on the bread you are making), and cover with the kitchen towel again. Let it proof again, then bake.
If you are going to use a one rise/proofing recipe - mix and kneed your dough, for into loaves, place into pans or on a baking sheet, cover with a clean kitchen towel and to allow to proof.
If you are making the dough and want to retard it - mix and kneed the dough, divide into loaf portions, roll into balls, oil the surfaces and place in a plastic bag - refrigerate until you are ready to use. Then, remove and proceed with the proofing and baking.