When is it safe to wash my baby with regular soap?

As soon as you want: Your baby doesn't do much to get themselves dirty, so most babies do not need a bath more than once or twice a week. Until the cord has fallen off and has healed, your baby's belly shouldn't be immersed in water, so that means sponge bathing. It's ok to use soap right after birth, just use a mild soap intended for infants.

Day 1!: Regular non-scented soap is ok for babies. However newborns generally don't need baths more than a couple times a week and more may cause their skin to dry out. If your baby develops a rash or dry skin using regular soap try a gentler baby body wash which may help. Using a baby shampoo (no sting!) is helpful, especially since it often gets in their eyes!

After navel heals up: After the navel has healed up, bathing with a "baby wash" combination shampoo/soap would be milder and not sting the eyes, compared to using regular soap. Be sure not to overwash the skin, because that would make the skin too dry and prone to more rashes. One or two baths a week is plenty. Sometimes, the "baby wash" is only needed on the scalp, in the neck, under the arms, and in the diaper area.