it will take a lot of sailing for the original holes to wear out...
then they can be drilled out and bushings installed.... personally, I would keep the original holes as long as possible, and wouldnt enlarge them until its necessary.
the holes wearing in an egg shaped manner is normal, but by the time its drilled for bushings, it will be round again and still in the same spot... any abnormal wear can be filled with an epoxy or jb weld and re-drilled for size to fit the bushings.... but it will take a long time for that kind of wear to take place.
dont attempt to fix something that isnt broke