I'm currently at 6/10 Dreamies. And yeah I done messed up TT. Accidentally moved out a dreamie. I'm considering how worth it it is to move out 16 villagers or just stop pursuing dreamies and keep the 6 I have and just let the last 4 come and go at random, cute or ugly. Even considering making a 2nd town to try to get the lost dreamie into so I can still enjoy them. At least that dreamie taught me a lot about how to only buy original (the house was very messed up) and what to do when they don't ping right away.
Depends really, you always run the risk of losing more dreamies when speed cycling in your main town. I let Whitney go a few months back and slowly cycled to get her back...basically I found other villagers I would like to experience and gradually cycled her out of my void. Didn't take very long even going slowly though. For me it wasn't worth doing it to fast as I had to plot reset every time I got a new villager, had to always be at 10 villagers to get a mover every few days. Found it best just to try and enjoy whoever moved in in the mean time.
The 4 days forward, check for mover, then 4 days back and check again is good. But if you don't get a mover once you've gone back 4 days just go forward one day at a time until you do. Then start the process again. That's the fastest way, providing you've got 10 villagers all the time.
I failed at it last night as I lost my favorite villager. I ended up just cycling everyone out (almost- somehow Julian held on) til I got back to where I could get Ankha and Tiffany back. Now I just need Fuchsia and my stupid mistake will mostly be undone but with half the town being randoms as I can't deal with this stress anymore so idec who moves in after I get Fuchsia. I keep going over in my head what I could have done wrong. I found a post my a player who experienced this same thing using the guide to moving villagers out so assumed there was an error. What I think I did was treated 9 villagers like 8 assuming I was getting a new move in but a dreamie would move out. The game is always getting itself back to 8 so you have to remember when you have 9 or 10!