Best overlap: 8:00 AM to 1:00 PM in Toronto is 1:00 PM to 6:00 PM in Reykjavik.
Keep meetings inside 8:00 AM to 1:00 PM in Toronto — that maps to 1:00 PM to 6:00 PM in Reykjavik. Reykjavik is 5 hours ahead of Toronto, leaving about 5 hours of daily overlap — enough for most meetings if you don't leave them too late in the day. These times hold for most of the year, but Toronto's daylight saving (which Reykjavik doesn't use) shifts them by an hour twice annually.
24/7 support sounds great until a P1 ticket falls into the gap between Manila signing off and Dublin signing on. Here is how to design a follow-the-sun support model that actually catches tickets at the boundary. -