I don’t think its completely unnecessary, it helps save some time

Only thing to add to what has already been said: Office related stuff will be your biggest issue. Personally I suffer a lot with the web version of the Office apps, so I recommend dual boot or VM for when using office.

I would only be swapping once and then having the windows SSD in the USB C hub. Would you still recommend that I install the SSD straight away in the laptop and set it up from there?

Its so weird for me sometimes seeing a post with 100+ upvotes and 0 comments. Happens more often than you would think