I would get your ANMC in asap, mine didn't take months last year. Send by private courier and not Royal mail, to speed things up and then check their online tracker regularly, you will see on there when a positive assessment has been made, way before you get the letter of determination you need. It seems to be the AHPRA nursing reg that is taking so long. Get everything ready for the State Sponsorship application then, and as soon as you have positive skills assessment, apply online, this is the only part that is free! Then you have 30 days to forward all your supporting documents, again use private courier for speed.
Meanwhile, you could look into a temp visa with an agency. I went through O'Grady Peyton, they have been helpful but I have gone for perm 176 rather then a temp visa.
All in all, get going quick and you may make it!