Salivary gland Botox effects, when does the jawline start to change?

My salivary gland area looks bulging, so I am self-conscious about my jawline whenever I take a selfie. It would be great if this could be improved with Botox injections.

I've looked into it and found that reviews regarding when the effects appear vary widely, so I'm asking if anyone has actually received the treatment. Typically, how many weeks after the procedure did you feel the salivary glands shrinking and the lines becoming more defined?