I shake my nurse bees into my cell starter. Nurse bees should already be producing RJ, no reason to try and get them producing it. I keep it going by adding new brood every 7 to 14 days. Doing this I almost always get large healthy cells and the few that might be small (maybe 2-4 out of 45) I pull out and don't use. I have been running 45 grafts every 7 days and moving them to the incubator after they are capped. I can keep the cell builders going all season this way. When I pick my frams of bood I try to find emerging brood with some young larvae. The young uncapped larvae keeps the chance of a mite from getting in the queen cells. I just make sure I check for queen cells in that frame when doing my 24-48 hour check of the cells. By the time I get to my 4th week of grafts my cell builders are busting out with bees.
is to raise the quality of the cells by getting the nurse bees "into practice" making RJ for the emergency cells they start, so they generally do a better job of building out larger, better supplied, queen cells for you.