Re: couple or three questions ive been pondering.
I can't answer for Mr. Palmer, but I can give you my thoughts.
1. Returning the mother colony returns queen pheromone, uncapped brood pheromone, and young emerging bees to the portion used as a cell builder. It is not for the benefit of the cells, but for the colony, that you recombine the two parts.
2. I consider grafting day as day 0.
3. By day 10 the pupa have matured enough to prevent damage to them from jarring the cells, also by day 10 the bees in the mating nucs will get the pheromones produced by cells ready for emerging. I have placed cells younger than 10 days, but I have had the bees destroy the cells more often than with 10 day old cells. Was age the cause? I don't know, but why take a chance if you don't have too.
42 + years - 24 colonies - IPM disciple - Naturally Skeptic