Well i guess it depends if you go fractional or 121. But since you didnt post this in fractional we will assume 121. The overnights really depend on the company and your seniority.
Usually there will be a combination of overnights and out and backs(day trips). The senior guys get to bid first and pick the trips they want. If the senior guys are commuting they will usually try and bid all overnights to reduce the amount of commuting. Then again if they live close and dont commute they might want all day trips so they can be home all the time. It just depends on the person.
So i guess what im trying to say is that you will have to wait and see. Being a new hire you might or might not get a lot of reserve time. Basically being the bottom guy/gal you will have to take whats left.
I would definitely plan on being away from home....thats just the name of the game in this business.