When it comes to potato salad I prefer to cut my potatoes into cubes AFTER I boil them. One of the top complaints about a potato salad is that it can get watery. This is often because the potato pieces are still wet. If you boil your potatoes BEFORE cutting them then they absorb less water and are drier and more firm when you cut them into pieces. This does work best if you plan on leaving the peel on (which I recommend for this dish) but even if you want to peel them you can remove the peel after the potatoes are boiled, before you cut them into cubes.