I just set up a small 23 liter aquarium for red fire shrimps. There is no shrimps in there.

I filled up the tank with water from a rain collector and mixed it with some mineralised water. This has been three days ago.

The guy in the shop told me to wait at least two weeks before I can put any shrimps in there. He also sold me a probing set to evaluate the water quality. Just three days in now and the water quality is now perfect according to the test.

Is there any reason to wait longer to buy shrimps?