Another trip?!??! Oh dear. My heart hurts for you. I can see feeling the way that you do. You were drowning and its like everyone assumed you would just somehow power through it. You did of course, but at what cost?

I actually think common sense says nip it in the bud now. He has a few months to be thinking about the trip length and may get emotionally tied to a specific plan. Or you may have friends or relatives suggest things that back you into a corner. If you go ahead and set expectations now you can plan together something that works for both of you. I wouldn't wait. You'll sleep easier if you get it out of the way. Plus, you may be able to feel less resentment if you have a chance to get off your chest how the way things went down made you feel. Lighten the load!