The first inspection cannot usually be made before April. 'Shirt Sleeve Weather' is the usual term applied to weather conducive to opening bee hives.
February and March are dangerous months for the bees. The Winter stores are depleted, the brood nest is expanding, there are more mouths to feed, and the weather does not often allow foraging to take place. The colony could starve, so the first thing the beekeeper will look for on the first Spring inspection will be the state of the food reserves, and if there is insufficient then the bees must be fed. Check for the queen, or at least the precence of the queen, eggs, larvae etc.
At this time of year, combs can be replaced and a general clean up of the hive can be achieved, then a queen excluder and the first honey super can be put in place, in preparation for the approaching days of plenty. By the end of April the brood nest is now covering seven or eight frames of comb.
Towards the end of the month reverse the brood hives where there are two well stocked brood boxes; alternatively move a frame of brood down and add two frames of foundation to the top brood box. Check that you have equipment as suggested in Jan/Feb.
Keep a water supply available such as a car tyre laid flat on the floor.
If you have a hive which is very strong take a frame of emerging brood from it and give the frame to a weaker hive.
Think about integrated pest management for Varroa control.
When a colony has over wintered on two brood boxes they can be reduced to one on a warm day in March by removing the lower box and placing any stores beside the brood in the upper box. About three weeks later add a brood box of foundation above the box with brood.