Everyone is always bringing up the “parsec” issue. Time to nerd-out for a few minutes. It's officially been explained as being part of the Kessel Run - ships depart from one central starting point and all travel out in different directions. The ship making the “Kessel run” goes from ship to ship switching out cargo, and then the distance that the ships have traveled from each other is measured, and Han was able to make the run before the ships got 12 parsecs apart. That is the “official” reason Han said that. In reality they probably didn't know that when they were filming it :-)