What brand is the projector? Look in the manual what it says while it is powering up. I know that the Hitachi ones don't respond to rs-232 while they're warming up and you better not touch them for the first couple of seconds.

If you need power sensing you just get a device that senses the power consumption change on the power cord of the projector.

What about taking the projector controls out of the activities you don't need it in?

I don't understand the trigger part (what do you mean by trigger?).

I'm sorry but you provided little information (regarding to the length of the text) of what you'd really like to achieve and what options you have.