You can advertise as soon as you issue the communication to your staff on the proposed changes.
You might be advertising new roles that those being placed at risk of redundancy may want to apply for and they have a legal right for preferential consideration.
Or you may be advertising opportunities because you need more resource alongside the restructure, and existing staff may wish to apply for sideways moves or promotion opportunities.
We recommend that you:
Be ready with a consistent and fair process of selection and try not to pre-judge the situation.