Many overwintered colonies are very strong. Queens are laying eggs full tilt. The early warm weather has put the bees about three weeks ahead of schedule. Pollen is coming in, but pollen patties are still being consumed.
Most hives are ready for reversals if they haven't been done already. Top box to bottom, bottom to top. This will give the queen more room to lay and spread the brood and bees throughout the hive. It will also make the bees put pollen and any nectar coming in everywhere in the hive instead of in a concentrated area.
Two deep colonies may be packed with bees and may be starting to think about swarming. Queens are very hard to get this time of year, so divides will maybe have to wait. Adding a third deep will buy some time with the added room. If the third box is foundation, it will be necessary to feed sugar water or ProSweet to get the bees to draw out wax cells. Remember, no feed means no wax.
Being the bees started this build up early this year, any colonies not treated for mites last year should have their mite load checked.
http://beelab.umn.edu/Resources/Free-bees/index.htm This is a link to the Univ of MN free bees. They demonstrate how to check the colony mite load.
If there is a high mite load, treating with Hopguard or Mite Away Quick strips is probably the most natural treatments right now. They are both food additives and work well controlling Varroa mites. Api-Guard should not be used as that is a fall only treatment.
Soon the dandelions will start coming out. The benefit of strong colonies will be dandelion honey collection. At the first sign of dandelions two supers should be added to a strong colony. Many overwintered colonies are still heavy with honey from last year, the bees will need a place to pack away the new incoming nectar.