Although each tank cycles differently, the "norm" is 4 to 6 weeks. I'm reading your comment about "taking water to the lfs for testing" as you don't own a test kit for ammonia, nitrites and nitrates. My best advice to you is....get one.
Clean up crews are very important to have, but not until your cycle is completed and your tank develops enough food for the crew to eat. My guess is you have a few weeks, at least, before you need any snails, crabs, etc.
Jim