There are really two things two things that one needs to consider before they graft for the first time in the season. The availability of drones is the first. To successfully raise queens one must have a plentiful supply of dones for mating and they must be mature drones. Drones in the larvae state when you graft won’t be mature enough for mating when the queen is ready. Instead you must be looking for capped drone brood at the minimum and preferably lots of capped brood and a few adult drones already emerging from their cells. The picture to the right is a good sign. This hive had lots of drone brood in the pupae/purple eye stage in the burr comb between supers plus a few newly emerged drones on April 2nd.
While the availability of drones is somewhat out of the beekeepers control and depends on the weather, it’s very possible to help things get an early start by feeding pollen or pollen substitute. Hives with plentiful resources (especially a protein source) will raise large numbers of drones.
The other factor to consider is the weather itself. While you can graft and manipulate the hive to set up cell builders and mating nucs while it is still relatively cool, queens simply won’t mate until the temperature is around 68-69 degrees or warmer without rain or too much wind. This unfortunately is completely outside the beekeepers control and extended forecasts are not accurate enough several weeks into the future when the larvae you just grafted will be a mature queen ready to mate. This makes early queen rearing difficult and somewhat of a gamble if there aren’t a couple good mating days in the 3 week window after a queen emerges from her cell.
For beginners I generally recommend waiting until May or later to do their first graft. Drones generally aren’t an issue then and the weather mid May and later when the queens will be ready to mate is usually much more reliable. For those willing to gamble it can be done nearly a month earlier with some care, but there is always the risk of a late April cold spell that lasts too long where your new queens will fail to mate and will simply turn into drone layers.