Generally speaking, you don't have to, but I suggest you dress formally, which will give people an impression and make people think that your attitude is very good and correct. Don't dress too childish or fancy. You know, there are people outside the mountain. When the old employees of the bank see you wearing this, they will think that you are too immature and incompetent, and they will think that you are too lazy to take the old employees seriously. Just wait until after the probation period. Don't give a bad impression before the probation period. Even if you pass the probation period in the future, people will have a bad impression on you.