I don't think you need to start saving resources until they actually announce the next event. having 50~80k of every resource is usually good enough for most events, which you'll be able to gather from the time they announce the next event anyway, or just guess about when they'll have the next event, and start 3-4 weeks in advance. It's probably better to spend the time on leveling ships instead, as higher leveled ships will make your life easier in the long run, and probably save you resources, buckets and sanity.