I have thoughts like that too. Not terribly uncommon.

If they're active thoughts where you make "plans" and/or buy "supplies", then it's definitely serious and you need to go to IP right away. But a lot of us here have passive sui thoughts, which is unfortunately "normal" behavior.

You're the best judge because you know yourself better than anyone else. If you think you're an immediate threat to yourself or others, you should definitely go to IP, although I understand it's not necessarily an easy thing to do. (I admit that I don't go to IP when I should go.)

Oh, and the other thing... If you're an impulsive person and you get these thoughts, it might be worthwhile considering IP. A lot of people make sui attempts without "planning". They just do it on impulse.