In full swing
Definition 1 of 1
Pro Tip 1/3Active Engagement
Used to describe a process that is energetically underway and participants are deeply involved. 
The auction was in full swing, with bidders shouting their offers.
Pro Tip 2/3Time Specific
Often implies that the event started earlier and will continue for some time yet. 
We reached the carnival when it was already in full swing.
Pro Tip 3/3High Energy
Suggests a lively or vibrant atmosphere with lots of activity. 
The dance floor was in full swing, with everyone moving to the music.