Specs do not address boot time at power on, in this case a end-device. Appears a digital output pin takes a certain amount of time to reach a steady-state condition after power applied. In my case this triggers a relay to turn on for some number of milliseconds. I could put a capacitor in the circuit that triggers a MOSFET relay driver. But what value for the capacitor? I will try to measure the boot time and update this question.
It should take less than 100ms but I would suggest waiting at least 1 second.