I get this question a lot when folks purchase a Nuc or a full Hive from me. It’s a good question and I remember well my own curiosity about how often, am I doing it too much or not enough, and so forth.
For any new beekeeper, I firmly believe that they should be going in and pulling every frame about once a week. Hopefully, they started with an honest-to-god Nuc (not a package or something that folks today call a Nuc which is just a package that has been queened by the seller) and have at least two of them. This is a rare opportunity to inspect an entire hive and only be dealing with between 4000 and 8000 bees. When the hive gets to full size, it will run from 30,000 to 60,000 bees and be an entirely different animal.
With so few bees, you will be able to reliably identify some of the key parts of the hive (capped brood, larvae, honey, pollen, etc…) You might even see your first egg or that elusive queen (it should be noted that I never laid eyes on the queen of either of my two first hives during the first Summer!) More importantly, this is the time to get comfortable going through the bees. By late June, the bees can become a bit agitated during inspections since nectar sources are low and all of their neighbors want to steal their honey! So, for the new beekeeper, once a week for 3 months is right on target. Even 2 months is good.
But, I do not believe this is necessary for someone who is experienced. For me, I make sure that I look into every hive at least once a month. By “look in”, I typically simply pull off all of the honey supers and the top brood chamber, pull the center frame from the bottom brood chamber and make sure that I see some evidence of the queen. Usually, larvae is good, but I do want to see capped worker brood (only capped drone brood can be a problem!) If I see that, I mark the hive for it’s next inspection in 4 weeks. Of course, there are other factors that might bring me back to the hive, such as checking honey supers or maybe creating late Nucs off of a particularly good queen line. But, these are all nice-to-have…my main Must Have is “check to be sure that I see evidence of a queen once a month”. If I do not see it on the center frame, I dig deeper to see if I have a problem.
Finally, since I am actively working on creating Nucs, I typically go into the hives once every two weeks during Apr, May and Jun. But, this is really just to create more hives.