We are planning a trip next year for 6 months......
Way to go @Heidi at, I wouldn't stress at all based on our experiences just enjoy the prep and the trip, if you can get the kids involved in the prep as well, listen to their ideas on places to go and incorporate them into your plans, that way they'll enjoy it even more when it comes to heading off, at least that's what we found, it sort of gave them a bit of ownership in the whole thing if that makes sense.
Dave