i'd change the keyword 'celebrities' to 'top of the social pyramid'. You want to start the social group at the top of the social pyramid of the respective social circle. Create a social clique, which everyone would be jumping off the ground to join. Facebook was started at Ivy League, which allowed it to spread like wildfire in colleges. Similarly Clubhouse was started in Silicon Valley with top VCs and Founders.

Of course, each social app goes through various inflection points and arguably celebrities is towards the peak end of it. Celebrities usually catch on once it's already going mainstream or has a mainstream appeal. For example, Twitter had already created strong base of engaged users before celebrities caught on.