Make sure to give common milk plenty of space.  If left alone, it will spread and create a large colony.  You can control the spread by collecting the seed pods and pulling up stray runners.  However, common milkweed has a great ecolgical value and monarchs rely on its big leaves for food, so consider letting it have a go.  It can be interplanted with other aggressive pollinator plants for a meadow look.  
 
I only have second year plants of this species.  They should bloom this summer.