Anytime anything changes!
After you've completed your profile with as much information as possible, we would recommend updating your profile whenever your circumstances change, particularly your work preferences.
Ensuring you are updating your "availability" if you are "interested in job offers" and "preferred work locations" can impact whether you are considered for a job post.
A helpful tip is having a monthly reminder in your diary to double-check your profile. Just as you are always developing, make sure your profile is developing with you!