French to Italian Marketing Human Resources Instructions for trainers in a world relevant food enterprise

I have also J-2 semaines
Context:
Planifier et préparer la réunion d'information de l'équipe de gestion à J-3 semaines
or
Planifier la réunion avec les équipiers à J-2 semaines

I would have expected J-3 or J-2 semaine and I would have translated "il giorno 3 della settimana". The plural form leaves me a little puzzled, so I thought better to ask for an explanation to someone more expert than me. I also have to precise that the documents were drafted in Switzerland

Many thanks for your time and help