Romford to stratford station>jubilee line?

At Stratford there are two flights of stairs leading down off the national rail platforms, if you stand with the station and shopping centre to your left, then the furthest stairway ahead of you is the easiest to use (so be towards the front of the train when you get on if you are in a hurry), since you only have to go down one flight, and then up a small flight to get to the jubilee line.