Once a week I do a full workout of sandbag training, and at the end I carry the bag for intervals; I bear hug and carry it twice down a hill, and carry it on a shoulder twice up a hill. Currrently I carry about a hundred lbs (The hill is about 125 yards give or take) and it takes me about 8 minutes to complete this "route." Currently I've just been increasing the distance of my route, but when should I start increasing the weight or working on completing the route in a shorter amount of time?

I'm training for wrestling, and a match is about 6 minutes if that is any help.