After the queen emerges from her cell (16th day), it takes her about a week for her exoskeleton to harden and for her to become sexually mature. She then makes a couple short flights to strengthen her wings and to orientate herself to her colony.
When she is ready to mate, she will fly to a drone congregation area (DCA) to find her mates. Mating occurs in mid-flight. The drone's endophallus gets ripped off and left behind in the queen during this process (called a mating sign) and the drone dies shortly thereafter.
The queen can go on several flights until she feels her spermatheca is full of drone sperm (and if the weather allows and isn’t raining). It's critical for the longevity and prosperity of the queen and her colony for her to mate with as many males as possible (usually 10-20 but can be more).
When the queen feels she is mated properly, she returns to the hive never to leave again unless the colony decides to swarm or abscond from their current home. The attendant bees are very excited upon her mating flight return to pull out all the drone endophallus’. More drone endophallus’ mean more chances of sperm and successful mating which equals a productive laying queen. The queen usually begins to lay eggs within 48 hours of return from her final mating flight.
If the queen can’t go on her mating flight(s) because of inclement weather, etc; she will only be able to lay unfertilized eggs (males). Queens fertilize their own eggs and these are females (workers). Queens who can only lay drones are called “drone layers”. Queens who run out of sperm are also drone layers. Having a drone laying queen is detrimental to a colony because workers are the bees who do all the work (foraging, raising young, etc.) in the colony. Drones' main purpose is to mate with queens.