Will my face shape really change noticeably if I get jaw Botox? I'm also curious about how long the effects last.

Lately, I've been particularly self-conscious about my jawline whenever I take photos, so I'm considering getting jaw Botox. My jaw isn't extremely angular, but perhaps because of my habit of clenching my teeth, it feels like my jaw muscles are a bit developed. Friends who get jaw Botox regularly say their facial lines have definitely softened, while another friend said she felt a difference after the first few sessions but isn't sure if she needs to keep getting it. I'm curious about when the effects usually start to show and how long they last. Also, rather than becoming too slim, I'd prefer just a slight reduction in jaw muscles to make my facial contours look natural; I'm wondering if this is possible with dosage adjustments. Has anyone experienced side effects like sunken cheeks or sagging? I'm a bit worried because I've seen online that if administered incorrectly, it can make your cheeks look even thinner. I'd also like to know what I absolutely must check during the consultation for my first jaw Botox session, and what questions I should ask to ensure the injection fits my face shape. Please give me advice based on actual experience, not just advertisements!