When you bring baby home, you're counting life by days and weeks, not months, and feedings are often measured one ounce at a time. There's a reason they call the first three months after birth a fourth trimester: Baby is still rapidly developing, except outside the womb — thank Mother Nature for not making you deliver an even bigger baby! Sure, every step is loaded with questions (Should I wake him to eat? Am I producing enough milk?), but keep in mind that no one knows your baby as you do — you're his mom, after all! Trust your instincts, mama, especially when it comes to the two greatest challenges of the first 100 days: eating and sleeping. From how much to when, where and how, feedings and sleep (or lack thereof) will become a huge part of your new-mom existence. The following are expert tips to help you handle these main events in your newborn's life.

Fill 'Em Up

All babies leave the hospital weighing less than when they were born. “It's normal to lose about 10 percent of weight in the first few days of life,” says Ari Brown M.D., pediatrician and co-author of Baby 411. Your job is to get him back to his birth weight by about day 10. This puts a lot of pressure on new moms, especially if breastfeeding. (If only we had ounce markers on our breasts to indicate how much baby is drinking!)

Nursing is oh-so-time-consuming and completely foreign if you've had little to no exposure. Take a breastfeeding class to learn the basics, but believe in your body: You and your baby instinctively know what to do. “My experience is that women who excessively prepare are fueled by a fear of breastfeeding not working out,” says Kathy Bradley IBCLC, a lactation consultant and childbirth educator who founded childbirth concierge.com, offering online support for every stage of pregnancy and new motherhood. “When mom is stressed, i.e. scared of not producing enough milk, those concerns can actually trigger unnecessary problems.” For a truly successful feeding session, you're going to have to relax.

Most hospitals have knowledgeable nurses and lactation consultants on staff. If you're not comfortable with the advice you receive from one person, ask someone else. There's plenty of support if you look for it. Deanna Erne is mom to 10-day-old Teddy. She's already attended breastfeeding support groups offered by two local hospitals. “It's a safe, supportive place to go with my baby where I can be part of a group of moms all going through the exact same thing,” she says. “Plus, you see how everyone nurses a little bit differently, so it gives me new tools to try.”