T-Mobile Retail Sales Associate interview questions

applied online, two days later got called in for an interview, interview was about an 1hr long with store manager then was sent to another close by store for a 2nd interview which was about 15 minutes long, got called 2 days later that i got the job, a week later started working

I've completed two interviews with T-Mobile, both were super laid back and the managers made me feel at home. They asked typical interview questions.. Right after my second interview, i received an email request for my background check. Today (a week after I submitted the information) I got another email with a copy of my background check, which has cleared. My questions are... how long do they take to make an offer? Do they do background checks on everyone, or only the people they intend on hiring? Update-- I got the job! Quite excited to join this amazing company!