Way earlier someone mentioned making a cheap fabric mockup before diving into the expensive fabric. I made a velvet dress nearly 2 decades ago but started with the lining, figured out All the tailored modifications on that before I cut any velvet.
Your right about making one with cheaper fabric first. Old sheets work well for that. Several years ago my son worked for a veterinarian. They referred to him as the minon. So for Halloween I made him a scrub like a minon