SSD with assigned drive letters

I obtained an SSD and connected it via USB.
I had to initialize it,
then create two simple partitions,
and format the partitions,
and assign drive letters (E: and F:)
before it would show up in Windows Explorer.

To test it, I coped audio files to both partitions. They played back without any problem.

Using a Recovery USB, I want to do a fresh install of Windows 10 Home in the first partition and use the second for data.
I could not assign C: to the first partition as C: is, what everyone knows.
However, I want it to be C: when Windows is on it. Probably the install will also created a D: Recovery partition within the first partition, but I don’t really care.

Will the fact that the SSD partitions already have assigned drive letters cause any difficulty?

Drive letters are assigned by the OS you boot from. You can have different drive letters under different OS.

Did you initialize the drive as MBR or GPT?

On BIOS disable fast boot and secure boot (you can turn it on after installation)

Windows can be installed in two ways: Legacy-MBR or UEFI-GPT
To install as Legacy-MBR you must boot the installation drive as Legacy
To install as UEFI-GPT you must boot the installation drive as UEFI.

As you have a new MB, you should install as UEFI-GPT
Detach any other drives (SATA or Power cable) from the MB. It's important or you may end with the OS in one drive and the boot loader on another.

During POST, press F12(?) to launch the boot menu. You will see two options for the USB drive. USB UEFI (Name) and USB (Name). Select USB UEFI (Name).
Go to install and delete ALL partitions on the SSD till you have one and only one unallocated space then create the two partitions, select the first one to install Win10 and then proceed.

If you don't want to use MS account, don't enable updates or connect to the internet during installation.

Clean Install Windows 10