Good to have. Not necessary but need to be in queue..
I agree with Srinivasan, it would be better to have an appointment, but if you are pressed for time just give it a go. You'll still need to wait for the card tho, maybe 3 weeks or so.
You can just walk in, there is a chance you may have to wait if they are busy.
Rather walking in, or making an appointment you won't be in there long. They lock the door during 11:30am- 12:00pm just incase you went during those times.
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