What is the best way to get an idea of what a carve will look like before it is actually carved?
It depends on what design software you are using.
I run vcarve pro and it has a preview window and ugs has a visualization window that tracks machine movement in near real time.
inkscape
Another vote for Camotics. I run every potential cut through the software and has saved me countless number of times. It’s free, Open-source and looks to be available for all platforms. My entire tool chain is OS and this is a main part of my arsenal.