So I've been thinking about getting two filters for my upcoming tank to help keep my water extra clean. Would it be better to add both filters at the beginning, or set up with 1 and then later on add the other one? thanks

I have a couple of two filter tanks, so that I can clean their media in alternance and not upset their bacterial life. Every second water change, I clean one set of media. It works fine and you can add them whenever you want.

Sounds good! I'm assuming the water stays nice and clear, right? That's always a great benefit!

Filters don't really keep the water clear. Most things that will cloud your water are too fine for a filter to have much effect. You'll clear your water with water changes, siphoning of gravel, management of biological wastes in the water and good management of biologically active filters.
To clarify water, there are pricey specialized filters of the sort photographers use, and uv is purported to help
2 filters won't make the water clearer, but they will improve the biologically based filtration if you manage them right..