Hello, and welcome! I started and finished my first coop and run this year. Like you, I started planning and building before I got the chicks. I spent a lot of time on this site looking at examples of coops on the coops page, reading posts in this forum, and eventually deciding what it was that I wanted my coop to be.
With time on my hands (and no chickens....yet), I was able to scavenge a lot of materials for free. That changed my plans a little bit, but not too much. In all, it was a wonderful process and I got time to spend with family while we built a bit here, a bit there.
I also read and listened when it came to slecting breeds. I wound up with 4 Barred rocks and 4 Buff Orpingtons. They're 4 months old now and are very docile. Some are even sweet.
Good luck!