scratch disks for laptop

Hi All.

I got stuck with my process of learning premier pro. Before I didnt care about scratch disks on my laptop as I worked on rly low video files, so i used all default set.

Actually I wanna work on 4k60fps, so I guess correct scratch disk settings really matter.

Here is my laptop spec:

Intel HD Graphics 530, NVIDIA GeForce GTX 960M

Intel Core i7-6700HQ

ram 16gb ddr4

256gb samsung 960 evo - system + programs

HDD Toshiba 1TB (MQ02ABD100H)

And here is my probably amateur question: How to set up scratch disk in premier pro for those 2 disks? What cfg will give best performance to work with 4k footage?