I grafted for the first time back on April 3rd. I grafted 20 larvae and 10 were accepted and fully drawn into queen cells. I put them into 10 nucs. As of today, only three have emerged. Is this normal? If not, how long should I wait before I assume that something went wrong with these fully-drawn queen cells? There are some emergency queen cells in some of these nucs and I'd like to utilize them if I can/need to.