I would say now is the time to be concerned ... Especially if you think you may act on it ... I've lived with what's known as "suicidal ideation" my whole life, but after finding a good mental health professional (one that is willing to explore the why of it with me without automatically freaking out and putting me in the hospital), I've come to understand why I do this and it has lessened the duration and intensity of these thoughts whenever I'm having a rough time coping and dealing with life now.