Make sure the time zone is set correctly for your group so that your email notifications arrive at the correct time.
1. On the top left side of the toolbar, click on All Groups (or the Group name) and then click Manage.
2. Select the Group you want to edit on the left sidebar and choose the Group Settings tab.
3. Scroll down to Timezones and select the appropriate time zone for your group. Don't forget to click Save Changes!