That's normally the way they do it. The announcement about the dates is normally made approx. a week before tickets go on sale. In 2024 the official party announcement was made May 6, 2024. Tickets went on sale for Disney resort guests on May 8, 2024 and for all guests on May 15, 2024.
This is how it was in 2024. There is no guarantee it will be the same in 2025 but, there will be time (days, a week?) between the announcement and tickets going on sale.
That being said, it's likely dates will be on similar days of the week to previous years and that the announcement will be made within the next 2-3 weeks. A lot of planning and prep can be done now.