Rather than discuss what you can expect -- the range from a large negative to a small positive is huge -- why not focus on a reasonable goal? Unless you have a strategy that you think can produce 30 points a month and then as you begin to execute it flawlessly 40 + points you should probably rethink your approach. On the other hand if you are a relatively new trader -- as I am sure you are -- if you have a strategy that you think will produce 200 points a month then you are clearly operating in fantasy land. Shoot for 6 to 10 points a week early on and be damned pleased to get to that point while you still have capital to exploit what you have going for you.
If your performance with your trading system is decent (like 60% or above) you can shoot for 1 or 2 pts a day on the ES scalping and working on not giving it back.