Hi Conrad, Yeah, my first reaction was WOW! LOL, for future works a general, no more than a third rule, is used for root and/or foliage reduction. Why is this? Glad you asked, because I'm pretty sure your tree will survive as many of the junies I did this to in my early days have also survived, barely maybe, but they hung on and did come back.
Ok, the thing is, we're not just going for survival, we need our trees to be robust, in optimal health and bursting with new growth. It is in this condition you can do your best work without slowing down the progress of the tree or endangering the health of the tree.
What's done is done and you can never go back for a new start, you can only go forward and make a new end. You have a nice abrupt bend to start and I'd put some nice jaunts in that long sweeper you have the wire on already. Try to get a branch on the outside of each bend. Your wire is a little streched out, too. Go to bonsai4me.com and look at wiring how to.
Myself I don't care for full cascade unless there's a really cool trunk to come off of. Just me, but I think with smaller pieces a top knot distracts somewhat from the smaller trunk. Looks a bit naked up there and if you got nothing to show best to keep your pants on. A good show for first time outta the gate. Learn from it and get another one, it's on! Rick