According to http://www.hivetool.com/guide/ the activities that we should be doing in April and May are:

• April
  • Swarm Control
  • Dividing a Colony
  • Installing a Package of Honey Bees
  • Transferring a Colony from a Box Hive to Modern Equipment
  • Using a Queen Excluder to Confine the Queen During a Honey Flow
• May
  • Supering a Colony
  • Hiving a Swarm

The early spring is already creating a lot of swarm catching opportunities. They can appear anywhere so keep your eyes open.