I would you feel if I told you I plan on telling my wife I won't try to have kids until she starts trying to take care of herself?
I kind of understand where you're coming from, what concerns do you have about how your wife takes care of herself?
This is a dangerous topic for my relationship. I must be prepared to be on my own.
Having children is a large responsibility and it's understandable that you want your wife to reach certain goals before starting a family. If there are issues with how your wife takes care of herself, you should talk with a professional like a family planning counselor so that those issues can be brought up in a nonjudgmental environment. If your wife hears from a professional that she needs to make changes, she'll be more open to do so compared to listening from you.
I'm not talking to her. NEVER! I'm going to put my foot down.
This isn't the right approach to your situation. You need to have communication with her about how you feel. If you don't communicate this your relationship is going to crumble before your very eyes.