in full swing
US /ɪn fʊl swɪŋ/
UK /ɪn fʊl swɪŋ/

1.
en plein essor, battre son plein
at the peak of activity or progress; fully active or operational
:
•
The party was in full swing by the time we arrived.
La fête battait son plein quand nous sommes arrivés.
•
Construction on the new building is now in full swing.
La construction du nouveau bâtiment bat maintenant son plein.