At what point do you tell someone you think you need to be professionally diagnosed with depression?

Tell your family or people who love and understand you as soon as possible. There's nothing wrong in talking about it and it may help you to have their support

If the person is so depressed or lethargic they can't seem to go about their daily lives. The problem is when you're depressed you lack motivation, and you need to be motivated to seek help. When a person can't even be motivated by their own happiness, they may need some encouragement to seek professional help.

When symptoms are not going away after 6 months at least. You should talk with a psychologist first and then you may talk with a psichriat about depression.

The point when I feel guilty or worthless of whatever has happened or I am unable to take clear decisions and feel sleep disturbances while constantly being sad for a long amount of time I can say that I need be professionally diagnosed with depression.

The clinical answer is when symptoms of depression persist for over two weeks. At this point, you may want to see a professional in order to get help with your mental illness, especially if you are experiencing darker thoughts like feeling worthless and wanting to die.

As soon as you find that its an obstacle in living life as you normally do, like when u dont want to eat or sleep and similar things. When u see the signs and it hinders your life in anyway no matter how small.

When they are experiencing changes that are starting to get debilitating on their daily life, and most of all, when they are not in the capacity to overcome it. Some people can recognize that they might be depressed and take precautionary steps, some can't.

If you believe that you're becoming unable to cope with your daily life, if you are consistently feeling low or your low mood is affecting your normal routine, then you should seek professional help.

When you feel worthless and feel like you have nothing to live for and cry a lot at small things or want to die

I most definitely relate to this question... I just came from this same position. After you start to notice symptoms, make sure you're paying attention to them and noticing if they're getting better or worse. If it starts to interfere with your day to day activities, I'd suggest talking to a doctor or counselor. It can be scary, but you need to remember that your mental health is your first priority and it's important to take care of yourself. Tell your doctor your symptoms at your next check up and they'll be able to help you take the next step by either giving you medication or suggesting counseling. Good luck!