Something to take in consideration for all groups:
As long as your group hasn't met a new group yet, they are separate story lines, that in the chronological sense might not have started at the same time. (If your story started a year before the other group, you can have your story span a year before you mention that you see the others) This means that you can have your story span multiple days when the others are still introducing themselves to each other on the first day. If you meet the other group you have to be more careful with this.