I would use two different disks, the one that you have already for windows and a second one for Linux. When you’re ready to install Linux Unplug the windows disk, so that you can’t screw it up ( been there, did that 😭) then when you need to use either the Linux or Windows Just choose the start up disk in bios at booting, usually F11, a tiny bit longer than dual booting, but it will save you a lot of hassle. Dual booting is rather dangerous as windows has the annoying habit of wiping Linux grub setups when updating, and Linux has the annoying habit of wiping everything, two different disks, much easier.