I need to wear an off-shoulder top, so I'm inquiring about Botox for my bulging trapezius muscles!

Hello! I'm getting ready to wear sleeveless or off-shoulder dresses for my upcoming vacation, but when I look in the mirror, the trapezius muscles running from my neck to my shoulders are bulging out. This makes my neck look short and my shoulder line look too bulky. I do a lot of computer work, so my posture isn't great, which seems to have caused my trapezius muscles to develop even more. I'm considering getting trapezius Botox to improve the fit. I'm curious how many weeks it usually takes to see the slimming effect on the bulging muscle lines if I get trapezius Botox at Maypure. I'm also looking forward to honest answers from those who have experienced it regarding pain, post-procedure stiffness in the arms and shoulders, and how long the effects last.