Every day. Many, many times. Every day.

I've been known to seek buying advice for things that I only use a few times a year -- like my bicycle. Or my bathroom scale. Well, OK, I use the scale nearly every day, but I really felt like I needed that body fat detecting doohickey and I don't think I've used it since the day I programmed it.

The point is, for something you're going to be using multiple times a day for the next few years, read a little bit about it first. Baby Products Guide Heather Corley has some great advice here. But if you choose not to listen to her and you buy 5 cases of newborn diapers on sale, when your baby outgrows them and you still have 3 cases left, all is not lost. You can always use them as Swiffer pads. They work especially well on the WetJet version.