The delays are designed to make sure that every device recieves every command that the Haromony sends.

Note, times are measured in milliseconds (as mentioned), so 1000 ms = 1 sec = 1 s.

Inter-key Delay:
The delay between any two successive commands. If you tweak the repeats (discussed later), many devices will work perfectly with a 0ms Inter-Key delay. 100 ms (0.1 s) is the best starting point for the vast majority of devices, though a very few need something longer.

Power Delay:
Most devices have a period after they recieve a power on command where they're busy starting up and won't accept any other IR commands. This tells the remote how long this period lasts so that it can wait until its over before it sends any more commands to that device.

Input Delay:
When you change inputs on many devices, the device also becomes very busy acuqiring and syncing with the new signal. As a result there is also a period (generally shorter than the Power-on delay as a Power-on necessarily includes a signal-acquisition period) when the device won't accept any IR commands. The Input Delay is the length of this period so that the Harmony can wait until the device is done changing inputs before it sends any additional commands.

Inter-Device delay:
OK, so an IR signal goes out. There are 4 or 5 or more electric eyes in front of you ready to recieve it. It reaches all of them, and each device tries to decode the signal. The problem is that if the device isn't familiar with the signal coming in, it has a very hard time knowing when that signal is over and the next one (wich may be for it) has started. As a result, most devices look for a period of "dead air" after each signal to make sure that its over. The Inter-device delay tells the Harmony how much dead air each device needs before being ready to accept a command. In multiple remote land, this is more than covered by the time it takes you to pick up the next remote, but its an important thing for the Harmony to know. For most devices 100 or 200 ms is adequate.

Repeats:
The vast majority of IR standards repeat the signal a few times to assure correct transmission. Most standards call for the signal to be transmitted 3 times (original + 2 repeats). For most devices, the Harmony defaults to transmit each command 4 times (original + 3 repeats). To change this, go under troubleshooting for the device and select "Not all commands recieved correctly" and then either too many or not all commands.

How to set and tweak the input and power-on delays:

The most reliable way to do this is to use a stopwatch. I usually remind people that there is a stopwatch in most cell phones so you don't try to go digging one out of a drawer somewhere. Press the power or next input key on the original remote (for the power - ovbiously we're talking about from the power-off state) and then wait until the device is up and running again. You can also try sending additional commands until it starts recieving. Stop the stopwatch. Add 1/2-1 second to your time and then you have it. Just enter it in milliseconds. (7.5 seconds = 7500 milliseconds). You can also try the one-one-thousand-two-one-thousand technique - but obviously its not as accurate.

Adjusting the inter-key delay: Start at 100 ms. If the remote works and is fast enough for you, you're done. If it doesn't work reliably, try increasing the inter-key delay up to 200 ms and then 1000. If the key isn't recieved reliably at 1000 ms (1 second per key), go under troubleshooting and play around with the number of repeats. (There could be some stranger problems too.)

If the remote is sluggish at this inter-key delay, drop it to 0 ms and tweak the repeats until it feels right. Like I said, 2 repeats is usually optimal for most devices.