In what order should I buy PC parts?

[StillOnConsole]

I'm building my first gaming PC. I already have my build planned out(here's the build if anyone is interested: https://pcpartpicker.com/list/yX3wzY) but I don't want to buy everything at once. My build comes out to about $700 USD and that's a lot for me to spend at once. My plan is to buy the parts one at a time and to have this done by August at the earliest and December at the latest. What part do you think I should buy first?

 

Edit: Thank you all for the responses! I bought the case since NewEgg was having a sale on it.

[Starelementpoke]

Case, PSU, RAM, storage. Since CPUs and GPUs can change and flux rather often, buying them last is a good idea, though it's still a better idea to buy all at once. 

[GDRRiley]

case, PSU, then get RAM,cpu,motherboard at once. storage and windows can wait.

[TheSLSAMG]

Honestly, buying everything at the same time is a better idea. You are able to make sure that all of your components work in a reasonable time frame (because sometimes there are factory defects, I had an Athlon X4 750K that overheated no matter what I did with it and a Gigabyte GA-78LMT-USB3 that wouldn't POST, both were brand new in box).

 

That being said, follow the users above me if you want to buy part-by-part.

[DimasRMDO]

I think it doesn't matter, you can get your GPU last since your CPU has integrated graphics.

Motherboard, CPU, RAM, storage, and PSU are needed to get started at least. Well you need your case as well but you can assemble your computer outside the case.

[w1nger1]

Do you have the means to test your parts? It is generally easier to get an exchange or refund if it is closer to your purchase date.

Anyway, if you have the patience, just wait for buy whatever parts when there are discounts, since it won't be a working PC regardless unless you have everything.

Black Friday/Cyber Monday is so far away but it's within your timetable.