No calls after being hired

I applied to work at a retail job where I was called in to interview on October 5. The manager seemed in a rush and didn't let me talk much but it seemed like he wanted me to work there. I was given the offer letter for a decent amount of starting pay which I accepted. He said someone would call me back when my background check went through to get me started part time. I submitted my information for the background check, and according to their online system it has been completed and received by the store since 1 week ago.

How long is a reasonable amount of time to wait for them to call me? Or should I be calling them soon?

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