The entire department (approx 20 people) were gathered and told that due to business needs, it would be restructured, and all employees would have to re apply for their jobs in accordance with new structure (yet to be announced).
This, we have been told will may result in 1 or 2 job losses.

We were advised that we would be interviewed accordingly, and if applicable, offered new position.

My question is, as the revised structure (and new job specs.) are not available as yet, and any interviews are a week or two away, is it possible for the employer to back date any notice period to the verbal announcement given, or should notice begin after the proposed interviews?