I know about hernias...Have one on my right side as we speak, in 2008 had my left testicle removed because of an old, old hernia, subsequent rupture and ensuing infection. This all happened because I was always a very durable, rugged guy who had no time to be hurt or to coddle himself. Pain goes away, I always believed, and it does...to gather it's forces. Speed bag should be ok, but if your repair procedure is so close, I would wait, get it fixed and not risk it.
By the way, when you jab, its best to have a quick turn of the shoulder and hip, but do not shift the weight on your feet.