Where can I install WP Multisite. Root folder or sub directory?

I am setting up WP Multisite and had read somewhere that it should be installed inthe root folder (for domain mapping purposes). Then I read that it can still be done, installing in a sub directory, and still get domain mapping to work.

On my hosting account, the main domain name is an old, no longer used domain. I would rather not use it. But, Bluehost is willing to switch my main domain to another one.

BUT, we still haven't decided the name we will be using. Focusing more on developing the network while another team is looking at the branding and marketing.

I just don't want it to be a total disaster once we decide the name, changing location of the installation, domain names, setups etc...

So here comes my question. Can I still install WP Multisite in a subdirectory and have domains map to our network?