Hello. We are having construction completed and I was forced to move a camellia on my property. (10 ft big beauty)
I've read other forums and I've done a treatment for root shock, fed it etc.
the leaves are still green and healthy looking but are drooping down and just stared falling off.

It's got teenie buds and what I've read is the advice to do a hard prune after it flowers so the plant will focus on root stimulation. but I wonder if I should do it now?

Also how often should I fertilize it?

I suspect that it will lose leaves for a while yet. Just don't let it dry out too much but don't keep it wet. Although some people will say give it fertilizer you absolutely should not! As far as pruning now I think I would wait a week or two and see how it looks then. BTW it may drop all its leaves but try to be patient.

I transplanted a Camellia in the middle of summer in California one time (it was in the way of a construction project).

I planted it in a shady spot, staked it so it wouldn't move and kept it moist. It took a couple years but recovered and is a beautiful shrub. I'm glad I made the effort.

If you lost too much of the root ball, and I can't imagine you didn't if your Camellia is 10 ft tall, I would prune it back a little. But no fertilizer. That will kill it for sure.