Is there a way to not render warm up frames in Movie Render Graph?

In movie render queue, I can set a large number of engine warm up count to let my particle system run for a while. But the only thing i can set in mrg is “Num Warm Up Frames” and it will try to render these many frames(but not writing to disk), it takes huge time to warm up.
Is there a workaround to this? or I missed some settings?