It has been an extremely extended winter/spring in the North, as you well know.
I can share that 16 days ago (April 9) when I first did a very superficial check of only a few frames in a couple hives that there were no larvae no brood and only a palm sized patch of 1 -2 day old eggs. That was right after the cold snap. When I finally unwrapped them and checked again 2 days ago, they were obviously getting ramped, by observing 3 1/2 to 6 frames mostly full of eggs, larvae, and those palm sized patches of capped brood. Expect emerging bee bombs and swarming in 2-3 weeks ;)
Some queens are slower to get going. Especially if they ended the long spring with a very small cluster left. If they are starting to bring in the willow dust, you are feeding syrup and patty, I would say she is well underway to be going full bore right now. However the size of the patch of brood you see will be limited by the size of the cluster over it. The queen may be laying more but the bees cannot care for cells laid beyond their cluster. Those will die and be eaten. More bees make more brood and more brood make more bees and more bees make more brood ..... It all starts with how many bees there are, plus a good queen of course.
Hope that helps!