When to start harvesting shrimp?

At what population of neocaridina would I be able to start removing 25-50 shrimp every week while maintaining a stable population? This is my breeding tank for the 1000 gallon planted tank. Currently I'd say there are about 200 in the breeding tank. I'm assuming I'd need about 800-900 before I can start regularly harvesting that much. But I wanted to hear from those experienced breeding shrimp and regularly removing shrimps weekly.