If you want to start designing with it already (which is not a great idea; it is still alpha), here's a Bootstrap 4 PSD template you can use: http://hackerthemes.com/blog/bootstrap-4-psd-template
It is a good reason to leave the room / team / project when "design a website" means "open photoshop".
It does nothing to help their consistency, since you cannot define common styles to be reused.
And it has a trickle-down effect, where any developer working with the files now needs a license to open the document.
Maybe a simple canned marketing website can be worth skipping the planning phase, but good luck doing anything complex without some mocks. As a designer who can code, I usually skip the hi-fi mockup stage myself, but that's because I do it instead on paper.