Stamping date automatically

Have an interesting one here. Have a form which will be used to track some training requirements. Have a completion date which they have asked to be calculated off the value of a status field. The status is by Default "Not Started", once the person will be starting the training that status will be changed to "In Progress" the completion date is then supposed to calculate to one year from the date the status field was changed to In Progress". One note, the status will continue to be changed as they progress, Completed etc.

Anyone know of a way where I can trigger that one year "timer" and have it stay fixed even after the status has changed? I am open to suggestions here.