You can hide the nightly rate shown on each calendar day so guests only see pricing after they select dates.
The availability calendar supports a price="no" attribute on the shortcode. It removes the per-day rate from the calendar cells. The booking box still shows the full price once a guest selects check-in and check-out dates.
To use it, add price="no" to your calendar shortcode directly, or contact support to apply it site-wide.
Related option. Changeover days can also be displayed as a single solid colour instead of a split cell.