A renovation puts a hundred decisions in front of you at once: which walls move, which tile, which faucet, what stays. Home renovation interior design is about making those decisions in the right order, before anyone starts building.

Usually in the gap between ideas and drawings. Finishes get picked one at a time, the contractor fills in whatever is missing, and the furniture comes last and doesn't fit the room it was meant for.
Your contractor runs the construction. The design, the selections, and the furniture are mine.

Plenty of renovations happen while the owner is somewhere else. Presentations happen over video and updates come to you, so the design keeps moving. More on that here.
The best time to call is before demolition starts, while everything can still change.