Add a new work rule.
The operating time, rental intervals and color of the new rule must match the old rule.
In the new rule, remove the checkbox
Show in colors section.
Set the checkbox
Ends (from the moment of booking) after 4 days.
After that, place a new work rule over the old one.
Now add a tip type
Specify the message that the booking is possible no later than 4 days.
Remove the checkbox
Apply even if there are missing rental intervals.
Include a tip only on the underlying (old) rule of work.
As a result, when booking at the intersection of the rules, the tip will not be displayed.
And when booking only on the old rule (that is, for example, from the 5th to the 10th day from the current moment), an error will be displayed.
See an example in action: