It is always best to have an appointment otherwise you will have to wait, but there are times you get lucky and get right in. It also depends which lab you go to. Some are not as busy as others. I suggest you read the reviews to help figure which one is best for you. Some only do a few labs, while others are full service.
You can go here but you should make an appointment. If you just show up it's first come first served after scheduled appointments. They will do there best to accommodate you but you'll need to be patient.
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