A thought regarding setting future Campaigns and sync schedules up as we have some clients now setting up campaigns up to 12 months ahead. If you want to activate campaign now so not have to worry about it in the future you would need to set up sync schedule to check daily for new contacts in the groups so when it's time to send its the latest list.
I think it would make sense to have an option xx hours or day before send date to do an auto sync schedule so brings latest group list over to send.
This would take a load of your sync servers and probably of clients machines also. We have 1 client that is looking at between 80 - 100 active capaigns all running in the future and have concerns what the load may be like and perfomance on Act.
If this is a one off future campaign seems pointless setting a sync schedule daily up to then when all you need is up to date group day before. I know you could set a reminder to activate campaign day before but this is marketing automation hey