Unfortunately, there is no "one size fits all" answer. It really varies from person to person. It all depends on what you have on your reports to start with, how successful you are at getting things removed (through PFD or GW), and how well you maintain things as you go along (no additional lates - keeping low utilization). Some people also have the misfortune of new collections popping up as they are in repair mode, and have to deal with the associated drop in points.
In reading these forums, I have seen people gain 100+ points in a matter of months, and others who gain less than 50 in a matter of years. Thus the saying - YMMV.