Start it whenever you want. If you want a desk clock to start automatically when you plug it in....download Kaloer Clock from the market.

 

+1 Kaloer Clock

 

Would be nice if you could set the HTC desktop clock to start when you plug it in. It's essentially useless otherwise.

 

How do I get my phone screen to stay on when plugged in to a charger? It's no longer doing that since upgrading to 2.1...

 

Menu > Settings > Applications > Development
Check 'Stay Awake'.

 

I use digital clock. It's the only clock I've found that displays big numbers in landscape mode, with customizable colors. You can't set it to start when you plug it in, though.

Regardless, I recommend this clock.

 

Kaloer Clock Awesome App!!!

 

The problem I have with any clock other than the desktop clock, is that the buttons on the bottom stay lit. With desktop clock they go out.

 

i just dpwnloaded Kaloer Clock and it works beautifully