There is no universal rule that says a buyer should always offer before auction or always wait. The right choice depends on the campaign.
Build the value range and walk-away number first. Then ask whether the vendor will genuinely sell early, which terms matter and how many buyers have taken actions that require time or cost. Open-home attendance is not the same as committed competition.
An early offer can work when the vendor values certainty and your terms create genuine value. It is weak when it merely reveals your interest and gives the campaign a new price signal. Waiting may preserve information when the vendor is committed to auction or serious buyer activity appears thinner than the presentation suggests.
The tactic follows the evidence. It does not replace it.