You are right Indian Army19890. Actually no theory have totally correct explanation regarding the begening of universe. That's why we also study about "simple steady theory". Big Bang theory in more developed only due to the reason that we have some relation and formulaes and support many other theories. We can only guess your question that 50 years 5000years or 50000years are too much short time to determine the deviation in the distance between two particles.
Sometimes, its better to see behind ourselves to enlighten our forward direction.