Just an interesting FYI fact.... The Arthur Murray studio's syllabus has the American Rumba starting with a forward step (for the man) with the left foot in a SQQ count. The Fred Astaire syllabus has the Rumba starting with a side step (for the man) with the left foot in a QQS count.

Like others have stated, it really doesn't matter to judges which way you start as long as your basic rhythm is correct.