First, take your time in finding a caregiver. Finding the right person to care for your most prized possession will be one of the first — and toughest — decisions you'll make as a working mom. There are a lot of things to consider: Do you want a more formal daycare environment, or a private nanny at home? Do you have family member who can help part- or full-time? How much can you afford? What kind of coverage will you need? You and your partner should start to discuss these topics way in advance, even while pregnant. Having a clear picture of what is best and most convenient for your family will help target your search early, cause less craziness during the process and ultimately help you feel more secure in your decision.
Once you've found the right person, definitely have him or her start early. We have a nanny, and one of the smartest things we did was hire her to start two weeks before I was scheduled back at work. During that time, I showed her where things were and and demonstrated any special instructions I had, and most importantly, I could see her interact with the baby and make sure both he and I were comfortable. Hiring early also gave me the opportunity to practice leaving the house gradually — first for an hour, then two, then four, etc. You'll have a chance to do things like get your hair cut or run errands while easing into being away from your baby for long amounts of time.