I think that it all applies: the bees come out when it's warm enough to :
- void waste
- reorient to the hive (or orient for the first times for bees born late in the fall just before or after the cluster forms) due to long enclosure and seasonal change in position of the sun
- possibly to collect water and keep an antennae out for any possible early appearance of nectar/pollen
probably in roughly that order... as well as other secret bee business that we haven't sussed out yet...!
Of my two hives, the larger is still using the lower entrance when they come out on warm days, while the younger/slightly smaller hive is using the upper entrance (small ventilation hole as described by Bush84, about 1/4 inch by 3/4 inch). Both consist of 2 mediums and both weigh about 84 lbs currently, so have similar stores available, but one would appear to be higher in the hive - or for some reason just like the upper exit?