Definitely Make an appointment. I went once without making an appointment and ended up waiting for 6 and a 1/2 hours Twiddling my thumbs.
If it's a weekend most definitely make an appointment. You can always just walk in, if your not close then call and they will help. Good luck.
I would recommend that you make an appointment before you head over to the store. They do accept walk-ins, however the wait time can be anything from 30 mins to a few hours.
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