Including team officials, more than 600 visitors are expected in Wanaka for the 10-day event starting on Saturday.
Organiser Arthur Klap said the $500,000 championships had attracted an "exceptionally high" quality of athlete.
"It is quite outstanding really. It is almost like a senior world championship. The depth in the snowboarding is really good . . .
"If people come up to watch they should see some fantastic athletes," Mr Klap said.
The event would also put New Zealand "centre stage" in the snowsports world, just weeks before the International Olympics Committee meets in September to decide on the Winter Games 2014 programme, he said.
The FIS congress has already voted to promote the snowboard slopestyle and freeski halfpipe and slopestyle events on to the Olympic programme alongside snowboard halfpipe.
The junior world championships features those four events among the nine disciplines available and the IOC is closely watching Wanaka to evaluate its organisation and see how events are received by the athletes and the public.
"It [the September meeting] is not the final decision, but it could be a key determiner," Mr Klap said.
Aerial and mogul freestyle skiing is not in the programme because New Zealand lacks suitable infrastructure for those disciplines.
Mr Klap said that had cost the games some entries from traditional freestyle skiing nations.
Despite replacing those disciplines with freeski halfpipe and slopestyle, freestyle numbers were still not as high as snowboard entries.
World champion halfpipe freeskier Jossi Wells (20), of Wanaka, has entered, but is still recovering from a broken ankle.
Mr Klap said the expensive event soaked up human and financial resources from Snow Sports New Zealand, but should bring money into Wanaka.
The Oakridge and Benbrae resorts are fully booked.
The New Zealand Winter Games cost $3.2 million to host last year, while a world cup standard event would cost about $180,000-$200,000 to hold, Mr Klap said.
He was happy with the level of media accreditation and delighted people had volunteered to help.
Snow Sports New Zealand would do its own economic impact assessment.
"We have got a record of when the teams are coming and leaving and how long they are staying, so from that we should get a pretty good indication.
"We will know the average bed nights and average spend."
Other benefits included New Zealand competitors not having to pay for travelling overseas for competition, and the opportunity for the NZ Winter Games team to test systems before the next games.
A date for the next NZ Winter Games has not been set.
The junior worlds was also providing an opportunity for Russian officials involved in the 2014 Winter Olympics to come to Wanaka and learn the systems, Mr Klap said.
"I think a real opportunity for the public is at 5pm next Friday to be standing on Helwick and Ardmore Streets and let the athletes know Wanaka is really excited about the teams being here," he said.
World Junior Champs
Where: Cardrona, Snow Park
When: August 21-31
Entries: 350
Welcoming parade: Ardmore, Helwick and Dunmore Sts, Wanaka, Friday, August 20 from 5pm
