Making particules be there at frame 1

I got some leaves flying , and they start emiting at frame 1 ,but at frame one there are no particules yet , if i press the unborn button , they are all togheter in the emitter , i want that at frame 1 there are allready like in frame 20 for example , flying around , but i cnnot tell blender now ( i guess ) to start emitting at frame -10 for example.

how can i fix this ?

thanx

In 2.47 there is a problem that does not allow to enter negative values in the start frame. So your only solution is to actually move your animation to frame 10 (use the NLA Editor for easy movement of keyframes) and then start rendering at frame 10 to end while haveing the particle system start at 1. 2.48 should solve the problem but I haven’t taken a look at the RC yet.