For most of my customers, I program a "Start" activity in which I turn on all devices. I also program the remaining activities to leave on all devices. It sounds like a pain and not very efficient, but we do get less complaints due to devices not turning on and proper switching. The a/v designer I work with also prefers customers to have the maximum source/zone combos so "start" also helps because I don't want someone accidentally turning off the zone 2 source because they changed zone 1 activity. In your case the start activity would help since the remaining activities would not encounter a blank hdmi input while that source is powering up. With that issue resolved, working thru the input setup again as suggested above would probably help if not completely correct the problem. Once the Harmony macro feature is implemented, you can probably use it to address the problem by programming the order of delays, device power on, and input select.