I certainly start planning the next one before starting the ones I've booked.
Every trip I'm considering/planning on taking in the next year or two is in a spreadsheet and I've got various things set up to notify me as deals come along that might influence when exactly I take those trips.
If you want to travel on a regular basis at low cost, doing that sort of thing is basically a necessity. I have more places I'd like to go than money or time.
Now, if you are looking at it as "two months from now I'm going to need another break from all this stress" when you haven't even left for your trip next week, that's concerning.