Predicted Attendance at Lucy's Birthday Party

Maria is planning a surprise birthday party for her friend Lucy. She has invited all of Lucy's closest friends and ordered a delicious chocolate cake. Maria is feeling excited but a little nervous about keeping it a secret. On the day of the party, if everything goes as planned, Lucy will walk in to a room full of friends shouting, 'Surprise!'

Based on Maria's plans, what is the most likely prediction about the event?