when you do a water change leave him in the tank and just take out 25% of the water and clean the sides. you dont need to scrub it each time.
also 8 hours before you buy the fish ? a nitrate cycle can take over a month and doesnt happen in 8 hours. mine took 3 weeks and i still had high nitrates. do understand we are not moaning but we want the best for your fishy friend. he may make it but puting him during a cycle is not good