Hard drive configuration for editing
Put everything you are working on/with on the SSD, if it's full put it on the fastest HDD you have avilable. 

You have a real beast there in terms of computing power. Your processor is quite powerful, your graphics card and RAM even more so. The thing that is most likely to become your performance bottleneck is the disk speed. And even with the best of HDDs, this will slow you down considerably, as HDDs disk speed is just not fast enough to read dozens of large video files simultaneously (for the Icon View of the Project Panel, for example). With a 500GB SSD, you have plenty of space. Windows 10 install size is about 11 GB. Premiere Pro, After Effects take up under 10GB in disk space. So even assuming you need to install some other software as well, you won't need more than 50~100GB for all that, which leaves you with 400GB~450GB for the video files. As you mentioned, put the scratch disks on it so that the preview files et c. can be loaded quickly. Then just fill your SSD with the files of your current project.

If you really need more space, put some files on the HDD and see how much it affects the loading speed. If the performance takes a big hit, you can still use proxies. And frankly, if you do have the budget for the kind of equipment you mentioned in your question, I find it reasonably to assume that you could even afford another large SSD if you really needed it.

Two quick tips regarding this: Buy the cheap SSDs, not the expensive ones, there's no noticable difference between them. And never use SSDs for permanent storage, always keep backups on external harddrives.