Start Where You End
What's unique about the deadlift – as opposed to the squat or bench press – is that it begins with a concentric, or overcoming, movement.
For a variety of reasons like leverages, mobility restrictions, etc., starting from the floor can be problematic for some people. One simple way to build context, especially as it relates to the starting position from the floor, is to start at the end (or top) with an eccentric, or yielding/negative, movement.
You'll essentially be performing an eccentric deadlift (RDL) until the barbell reaches the ground. When I have my athletes do this drill I'll stop them once they hit the floor and say, "Feel that position you're in right now? That's what I want to see and for you to feel when you begin from the floor."
It's a foolproof way to help build familiarity.