The queenless split is made of frames of mostly capped brood and older larvae (4 days or older).  Frames of young larvae and eggs should be avoided.  If there are eggs and young larvae, the colony may begin rearing their own queen and not accept the queen cell.  The queen cell needs to be kept warm in the new colony.  Placing the queen cell on a frame of brood will help ensure the queen cell is kept warm and cared for along with the capped brood.  The split needs a good population of bees to keep the brood and queen cell warm.  Queen cells can be handled either just after capping or just before the queen emerges.  Between 2 days after capping and 2 days before emergence, the queen is very susceptible to damage from handling and temperature changes; this is the metamorphic phase of the queen’s development.  The queen must emerge from the cell, let her wing muscles develop and then go on her mating flight(s). The queen will typically start laying a week or two after emerging from the cell.

Checkout the demo video below