I'm considering getting Botox. What is the treatment cycle?

I feel like my square jaw muscles and the fine lines between my eyebrows and around my eyes are getting deeper, so I am seriously considering getting Botox.

Although everyone around me says that Botox is a simple procedure, I am worried about safety and side effects now that I am actually planning to get it myself, so I decided to post this question.
My biggest question is how often I should get Botox injections regularly once I start to maintain the effects.
I heard that if you miss the average treatment cycle or get injections too frequently, you might develop resistance, and eventually, the Botox might not be effective at all.
I am actually worried about the high probability of developing tolerance side effects.
Also, I am curious if the treatment cycle remains similar to that of the face when receiving Botox for body line improvement purposes, such as for trapezius muscles or calves, in addition to square jaws or wrinkles.
How many days after a Botox procedure do noticeable effects usually start to appear?
Also, I would appreciate detailed advice from those with experience on whether it is safe to immediately resume daily activities, such as washing my face, applying makeup, and doing light exercise, on the day of the procedure.