What to wear for my first day?

Okay well last week I had an interview/ testing/ everything with a call center that I got hired on at and I was seriously over dressed, I wore a black and red top, nothing fancy, and black slacks with low heels. Everyone else showed up in jeans, T-shirts, and sneakers. The interviewer even wore capri's and flip-flops lol. So today is going to be my first day and everyone is telling me to dress really nice again but they said buisness casual, which my husband (who also works there) said is just nothing revealing. But now I'm scared I will go in Jeans and a T-shirt and everyone else will be in slacks and skirts. Btw I see people come out everyday in pj pants and house shoes. I'm torn, casual to fit in or nice because its a first day??? Ugh!!!! Help :(