Rump Roast in a Crock Pot?

I have a 3 1/2 pound rump roast and i would like to cook it tomorrow for dinner but im just not sure how long i should cook it for on low? And also when should i add the Veggies? one of my friends told me to add them im the beginning when i first put the meat in but wouldn't that make them all mushy and gross by the time the actual meat is done?.