Inquiry regarding square jaw Botox effects and treatment cycle

Perhaps because I usually enjoy eating hard foods like squid or gum, the muscles on both sides of my jaw are particularly well-developed. I get stressed every time I look in the mirror because my square jaw makes my face look wide and gives me a strong impression. 

I'm too scared to even think about major surgery, I am considering a relatively simple square jaw Botox procedure, and I am wondering how long it usually takes for the effects to appear after the injection. 

And I heard that it's good to get injections periodically before the muscles grow back, At Maypure, how often do you usually recommend repeat treatments? I would also appreciate it if you could let me know what precautions I should take regarding daily activities and meals on the day of the procedure.