How do start up from a cold start in realistic mode?

[Freycinet]

Ok, I was a bit fast in my first posting...

I open the fuel cock.
I put mixture to rich
I choose fine prop pitch
I turn on the magnetos
I set the throttle to around 20%
I switch on the engine with "I"
...But then the engine just gives a little puff, the prop turns a few times and then nothing...

- Play the throttle? How?

Thanks!