Ah - there is no need to ramp it up slowly - you just need to dose accurately. I suggest two half doses, 12 hours apart, adjusting the second dose to reach 100%. Then retest 4 hours later to confirm the dose. Dealers put fish into full copper all the time with no issues.
There is a risk, where people take that to the extreme, and ramp up copper over, say, 5+ days. That can allow disease issues to become active. Then, when the fish start to show symptoms, the person freaks out, thinking it is the copper, they pull the copper and the fish quickly succumbs to the disease - yet the aquarist blames "copper poisoning"....
Jay