I consider my son a fairly heavy wetter, but the Planet Wise size 1 diaper cover works well on him during the day. He goes two to four hours between diaper changes. However, I have not had much luck with the cover at night. Although I use the size 2 on my preschool daughter overnight and have since she was a toddler, I need far more absorbency at night for my son than the cover holds. Right now I use a medium Best Bottom Diapers insert with an overnight doubler, which are too large to fit inside the Planet Wise size 1 diaper cover.
My son weighed 7 pounds and birth and could wear the Planet Wise size 1 diaper cover on the smallest rise setting and with one set of waist snaps exposed. The diaper fit snuggly, so I agree that slightly smaller babies down to 6 pounds could wear the cover without any problems. By ten weeks and a little over 12 pounds, he wore the cover on the largest rise setting with two sets of waist snaps exposed. At four months and 15 pounds and again at six months and 17 pounds, he wore the cover on the largest rise setting with four sets of waist snaps exposed.
During the day, I generally like the Planet Wise size 1 diaper cover on my son. The double leg gussets are excellent at containing messes, especially runny EBF poop. I also appreciate the interior flaps of the cover, which help hold an insert or another absorbent diaper in place. My only complaint is that sometimes the cotton exterior wicks moisture from inside the diaper. Of all my one-size covers, I have the most trouble with wicking with my Planet Wise covers. I must therefore be vigilant to change my son often enough. Otherwise, the cover does a good job of containing wetness and messes.
I am pretty happy in general with the Planet Wise size 1 diaper cover on my son. The double leg gussets help contain messes while the interior flaps hold inserts firmly in place. I do consider the cover a bit pricy at $17.95 each, but the size 1 version fits a baby longer than many other newborn diapers with a recommended weight range of 6 to 18 pounds. I also find that the cotton material on the outside of the cover takes longer to dry and occasionally wicks moisture. However, I overall rate the Planet Wise size 1 diaper cover very highly as a newborn cover that fits well into infancy.