"Some schools will start preparing the year before," he said.
"It is starting to get earlier and earlier each year as, mainly the girls, get more and more excited.
"It is one of the things students look forward to when they go back to school from the holidays."
Secondary Principals' Association president Tom Parsons said school balls were a highlight of the school year.
"Preparation and planning is key to everything these days and coming out of the global financial crises there are more and more functions being planned.
"Due to the attention that is placed on these events, school management is also being more and more particular that all i's are dotted."
Yesterday's expo, in its eighth year, attracted thousands of students from Waikato, the Coromandel, Bay of Plenty and Northland.
First-time exhibitor, Sue Gray of Hire Plants, said the business was expecting to cater for up to 25 school balls, supplying plants for themes such as Willy Wonka and The Great Gatsby.
"Most of them are happening in June or July so they start getting things rolling along now," she said.
Events seemed to also be getting more extravagant, she said.
"Sometimes the private school parents come on board and give a bigger free range with a bigger theme than some others."
There is more than two months until the Pullman Hotel will be transformed into a night in New York, but a meticulous Epsom Girls' Grammar School organising committee started getting their ball rolling in February.
Close to 500 Year 13 students and their partners will attend the May 30 New York State of Mind-themed event at the upmarket city centre hotel.
Tessa Boyd is heading the 15 students tasked with putting the event together, and said most items on the to-do list have already been crossed off.
"We started at the beginning of the year when we first started back at school," she said. "We split the committee into a few things so some people organised budgeting; some organised prizes; tickets and posters and the design of them; on-the-night duties; decorations and the food."
A DJ has been booked as well as three photographers, four photo booths and enough decorations to turn the hotel into Times Square by night. She said the final ticket price was not yet known, but would be under $100 for students at the decile 9 public school.
Aside from event logistics, students were also well prepared for the big night. Fellow Epsom Girls' organiser Lucy Armstrong said students booked their hair and makeup as soon as the ball date was announced. "There are so many people at our school and if you want to go somewhere good like M.A.C you have to book it the day you find out."
Most students already had organised their dresses, said Maddie Kidd, 16. "Most people buy online because there aren't enough dress shops in Auckland for everyone to have something different."