I'm thinking of getting Botox for the first time. Is it okay?

I have a habit of clenching my teeth, so my jaw feels like it's getting bigger, and I'm considering getting Botox. I became interested after a friend told me her facial contours became much softer after getting it, but I'm also worried since it's my first time. I'm especially concerned about my facial expressions looking unnatural, so I'm wondering if the changes tend to look natural. I'd also like to know when the effects start to appear and how long the results last. I've seen many reviews saying their jaw muscles definitely shrank after getting Botox, but is there a big difference from person to person? I've also heard the procedure is quick, so I'm curious if it actually finishes quickly. I have a low tolerance for pain, so I'm concerned about the pain and bruising associated with the injection. I would appreciate honest reviews from those who have had it done.