[kabdib]

I've been on teams where newcomers have shown up in suits, and we politely told them "We don't wear suits here." They started showing up in jeans.

I felt a little bad, but honestly they fit in better after that.

[Alupis]

Usually when you're new and don't already know the dress code, you show up 1 step above what you guess would be acceptable. Typically it's better to be over-dressed for a day or two rather than be under-dressed (fear or looking unprofessional/not serious).