Switching on xbox360 in a correct way?

the HDMI channel of an LCD TV normally needs a signal detection to stay in a HDMI channel. so when I switch on the TV first, I cannot switch the channel to the HDMI channel which is for my xbox when my xbox is off. I have to switch on the xbox first then quickly switch the TV channel. However, an xbox needs a display out READY so that it can be started. sometimes when I take a longer time to switch the tv channel, the tv could detect the hdmi channel but it stays blank. so what is the correct way to work it?