For caution or safety I would recommend only adding one or two at a time even though it is a pain to QT separately.
I don't know your system personally or could I tell you exactly how large the bacteria level is currently in there.
I would however if it were mine and I knew I maintained the beneficial bacteria from feeding that I would still only add the fish one or two at a time and continue to test the tank for signs of ammonia.
After I added the 1 or 2 fish and had zero ammonia from the fish and feeding them I would be confident in adding more.
It is always better to go slow, be safe, then to crash the tank.
Good luck and happy reefing.