If the tank wasn't fully "ready", that is definitely an issue.
If the fish had Brooklynella however, it would have been sick no matter how perfect the parameters.
I'm not dismissing the notion that OP might have moved a bit too soon - that is a possibility and definitely needs to be addressed - but it likely would not have made a difference in this instance.
If parameters weren't quite settled, it could possibly have accelerated the appearance of symptoms (stressed fish = more vulnerable) - but sooner or later, if it was brewing this infestation, it would have become apparent.
Jenn
