That's the Campaign.cfg entry for the Mission to be loaded, so it will load the file between those dates. The individual groups should "spawn" as scheduled in the mis file itself as called, and / or update if after the date of occurrence, if the group is still "active", which - if I'm remembering correctly, will be finished by the 15th... maybe. Just a pinch of "overhead", in case one of them encounters your boat, I suppose...
