Auto-Cue

Auto-cue will skip the silence at the start of the song. You can turn this on for all songs (in preferences), or you can manually do it by pressing the small "Auto-cue" button in the main kJams Browser window (to the right of the "Next Track" button).

It may not be desirable for some songs, which expect you to start singing before the first bit of music (however most songs like that will give you a little "tuning prompt" indicating the pitch of the first note to be sung, so it's not a problem.

In Preferences

Below you can see "Skip Silence at Start of Song", and also "Skip Silence at End of Song"

In the Browser Window

Below you can see "Auto-Cue", the 5th item down from the top