Why is this 'ceremony' titled "Is it shabbos yet"?
It's not. There is no official "ceremony".
The Rebbe encouraged young girls to light Shabbos candles from the age of three. Shluchim use their daughter's third birthdays to create events to mark the launch of their daughter lighting Shabbos candles, and to encourage other women who do not yet light Shabbos candles to do so. Someone came up with the idea of doing a video version of "Is It Shabbos Yet" at one such party. That idea took off and many shluchim do the same thing.