I remember when I was starting out, I had the exact problem. I literally had zero idea where the plane was in relation to the ground, either how far away, or even whether I was lined up with the runway. At one point I even talked my wife into going out a bit beyond the runway, and raising her hand when the plane passed over her head. Or she would site down the runway and tell me when I was lined up. Actually, I don't think it helped. After a while, I just knew. It happened just as slowly as knowing which way to turn whether the plane was coming or going. It just happened.