How open the wife wishes to be with her husband on all the details of observing taharat hamishpacha varies from community to community and from couple to couple. However, it is standard practice for a wife to inform her husband in advance when she expects to immerse in the mikveh. That way, the couple can make any appropriate arrangements or plans for that evening. They can also prepare emotionally and spiritually for mikveh night.
Ideally, your wife would immerse
on time. At busy times, there is often no one night that is clearly better than others. However, should something specific make it very difficult for her to immerse, and should you both agree to it, she could immerse the following night.
