Fashionista-in-training Harper Beckham got to practice her (newly-acquired) walking skills in an extra special venue Saturday afternoon.

As her mom, Victoria, got ready to show her Spring/Summer 2013 collection at the New York Public Library's storied Astor Hall, she snapped a photo of Harper, 14 months, toddling down her makeshift catwalk.

"Testing the runway!" Beckham, 38, wrote in the caption accompanying the picture.

In the exhausting days leading up to her show, Beckham -- busy balancing last-minute adjustments to her designs with Fashion Week appearances -- admitted the sleep deprivation was starting to catch up with her.

"After three hours of sleep I still feel like an old bag!" she tweeted Friday, sharing a picture of herself wearing a giant handbag over her head as she typed away on her laptop.

Her hard work paid off on Sunday however -- show attendees had nothing but good things to say about Beckham's latest designs.

As a Los Angeles Times fashion critic wrote, "A knockout. Beckham's collection is really evolving . . . The brand isn't just about Beckham anymore, it's about her customer."