Bro, you used the word experts very scary doubt got any bros dare to reply.
I am not expert but here's what I do with success so far.
Setup QT, keep all fish in QT under normal condition (SG) w/o use of copper for 2 weeks. Observe for signs of ich.
No signs of ich then you may introduce the fish into main tank.
If ich infection then either apply hypo for 2 weeks or use copper at 0.5mg/l for 2 weeks.
Note for hypo at 2 weeks, you will need to shift the fish to another QT and raise the salinity back to normal levels before transfering the fishes back to the main tank.