Brussels is 6 hours ahead of Montreal
Best overlap: 8:00 AM to 12:00 PM in Montreal is 2:00 PM to 6:00 PM in Brussels.
Plan around 8:00 AM to 12:00 PM in Montreal, which is 2:00 PM to 6:00 PM in Brussels, to catch everyone during office hours. A 4-hour overlap gives you a workable daily window; aim for earlier in it to avoid clipping the end of someone's day.