"The protocol was that you were not able to sail the new boats until the first of April next year ... it will be delayed until June."
The America's Cup protocol currently states that the first boat is not permitted to be launched prior to March 31, 2019, ahead of a series of preliminary regattas to be raced internationally.
Organisers were hoping to have two World Series events for challenger teams and the defender to line up against each other, with the first opportunity confirmed for next October in Sardinia.
However, Montgomery said the delayed protocol would rule out the opportunity of a second event, ultimately putting a strain on preparations for the 37th America's Cup.
"It will be a more compressed time because the dates for the America's Cup, March 2021, and for the Prada Cup ... will not be shifted," he said.
"That just puts a tighter period on it and therefore there will only be one regatta in the World Series of the America's Cup."
The deadline for entries close today with Montgomery expecting at least three more challengers to be confirmed for the Auld Mug, including one from the Netherlands.
There are currently three confirmed challengers - Italian syndicate Luna Rossa, American Magic, and INEOS TEAM UK.
"Team New Zealand are encouraging them so I'm expecting at least a couple, if not three and certainly I think the Netherlands could be one of them," Montgomery said.
"The Netherlands could definitely be serious, maybe one out of Italy, and who knows out of China and Norway, we'll have to wait and see."