These are known as "cell starters"
Bees will start building queen cells under three impulses - swarming, sepersedure and emergency. These are all used in a variety of ways by the various methods of "artificial" cell building by beekeepers. In some cases there is a combination.
Some methods use queenless bees to start queen cells, usually under the emergency impulse, then after a short time, usually 24 hours, will transfer the started cells to a queenright colony to finish building them. The former are called "cell starters", the latter "cell finishers".