Every listing has a production period. Professional photography is booked and shot. Floor plans are drawn. The brochure is written. A virtual tour is produced. Through all of it, the property is real, the decision to sell or let has been made, and nobody searching can see it.
Head Start is for that period. The agent publishes early with what exists on day one: one photograph, the key facts, and the BER. The polish follows at full listing. Nothing is held back and nothing is replaced; something is simply visible sooner.