"My phone is just ringing and ringing," Berman said. "I'm so excited. And my customers are calling me, as if I am his grandmother."
Now that the teeny-tiny royal will rightfully claim his blue bassinet, retailers like Berman are hoping we'll celebrate and buy, buy, buy for the babies in our own lives.
After all, this is the first royal in line to be king born since Prince Harry almost 30 years ago, and in this era of Internet and Instagram, that makes the newbie an instant world celebrity.
That his parents Kate and William are well-liked, not to mention trendy and modern, means parents will be paying attention.
"We have a young, beautiful, relatable princess, and we just feel that she's a nice person," said Erin Elmore, 35, the Rittenhouse Square mother of 3-month-old Royce. ". . . People are going to be dying to see that post-pregnancy body, how she's doing and how she's dressing the baby."
Days after the duchess' pregnancy became known, royal baby items went front and center.
As part of the Wait for Kate, Center City's Hotel Palomar began offering a Babymoon package last week with a prenatal massage, mocktails, and salty treats for expectant moms.
Cherry Hill-based Classic Cake is selling a royal cupcake in honor of the new heir, a yellow-cake confection with oranges, raisins, and English walnuts iced with buttercream.
"Happy Birthday, Prince," said Robert Bennett, Classic Cake's executive chef. "As a father of two boys myself, I wanted to congratulate them with my ode to an English Christmas cake."
Perhaps you want to eat that off a set of royal-themed china courtesy of English company Royal Crown Derby?
Safian & Rudolph and Bernie Robbins both are marketing royal-inspired push presents - that special gift grateful spouses bestow on post-labor wives - including everything from monogrammed pendants to blue sapphire (Kate's engagement stone) or ruby (the baby's birthstone) rings and necklaces.
Fashionistas, of course, are focusing on the clothes. How to dress a hip prince to show that he's down with the people?
The fashion-focused assume the boy won't be decked out in the kind of conspicuous Hermes and Lanvin gear that new parents Kanye West and Kim Kardashian reportedly bought for little North.
"This baby signifies a return to the elegant," said Berman, who expects his clothes to be more lovely than expensive. And with clothing labels out there called Royal Baby, they will be wholly appropriate.
"It's all about beautiful hand-smocking, and hand-knit sweaters. The finest of plush toys and swaddling blankets and monograms . . . things will be monogrammed."
At Born Yesterday, another children's store in Rittenhouse Square, shoppers have been gravitating toward Magnolia Baby onesies with double-decker buses and palace guards, part of its British Invasion collection. The store also is selling child-size guitars with giant Union Jacks on them.
"We've had them for about three weeks," said Kim Pierce, a buyer at Born Yesterday. "They are just so cute, and people are really enthusiastic about anything British on baby stuff."
Brittany Bollard, a former celebrity stylist and owner of baby boutique Hatch in Ambler, posted on Facebook that she was planning to carry layettes by Magnificent Baby - with magnetic closures perfect for new dads like Prince William - that feature the Union Jack.
Bollard said she's also carrying English sweater coats or pram coats by Powell Craft, the same label that William and Harry wore as children.
"Kate has been such a fashion icon," said Bollard, mother of an 18-month-old. "She's going to be classic and so very current."
As the Duchess of Cambridge embraces motherhood, she'll likely continue to influence the parental landscape with the choices she makes: How will she get back in shape - protein shakes or early-morning runs? Will she breast-feed? In public? Will she stroll or carry? Disposable diapers or cloth? Will baby's clothes be eco-friendly? Made in the U.K.? And what will she get for a push present? (All eyes are on you for that, William.)
"She has this opportunity to be a role model to the world," said blogger Paige Wolfe, eco-friendly mom of two. "Her fashion and lifestyle choices will be so emulated."
Bollard agreed, but was eager to give Kate a break from leader of the free baby world. After all, it's hard being a new mom - even a royal one.
"It's got to be tough work being a princess and a parent," Bollard said.
Contact Elizabeth Wellington at 215-854-2704. Follow her on Twitter at ewellingtonphl.