Found this interesting about capping times for emergency queen cells, which is often of concern when making splits.

"The average interval from egg laying to queen cell capping was 8.8 days and ranged from 7 to 12 days. The average interval from queen cell capping to queen emergence was 7.2 days and ranged from 5 to 8 days. The whole development time from egg laying to queen emergence was 15.7 days, ranging from 14 to 18 days. The age of brood at the moment of dequeening positively correlated with both the time of capping and the total queen development time. The average age of brood (at time of dequeening) around which queen cells were built was 3.0 days. However, higher proportions of queen cells with younger larvae were destroyed; in effect, the age of brood at dequeening from which queens emerged was 3.4 days. "

The experiment used only 4 colonies.

http://www.edpsciences.org/articles/...004/M4004.html

Emergency queen rearing in honeybee colonies with brood of known age p. 275
Adam Tofilski and Krystyna Czekonska

Apidologie
Vol. 35 No. 3 (May-June 2004)