The question is really how long after applying VDD until the MAX9723 is stable, and then when is it safe to disable the /SHDN pin? Keep in mind that the VDD supply will not stabilize instantly after it is enabled. Depending on the current drive strength of the rail and the amount of bypass capacitance, it could take as much as 100ms for the rail to settle after being enabled.
The recommendation is to measure the VDD enable response time to see how long it takes for the rail to stabilize and then wait an additional 10ms to disable the /SHDN control line.
The recommendation is to measure the VDD enable response time to see how long it takes for the rail to stabilize and then wait an additional 10ms to disable the /SHDN control line.