I just built mine. Bought the parts over a few days and put it together over 2 or 3 days. First day I went to Microcenter I got a screen, Mobo and CPU, 2 days later I got the case m2, hdd and psu and did the setting up that day.
Take your time. From the getgo have cable management in mind. You don't want cable clutter and if you take the time to do it in the very beginning, organizing as you go along, your computer will thank you in the way it looks and the way it cools.
And just today I bought the cpu cooler, ram, disk drive, and a case fan. Still waiting on the GPU I want to be available so for now I just put in my old one.
Excited to get it finished and closed up