Skip the formalin dip - way too harsh unless you use a low dose, then it's not effective. There is also a huge human health issue with it.
If the angel is coming straight from Biota (who gets them from Indonesia) and it did NOT go through any other system (LFS, wholesaler, etc.) you can pretty safely by-pass the copper and prazi, at least just go through an observational phase and be ready to treat. If it got mixed with any wild caught fish along the way, you'll need to run it through a full quarantine, copper at 2 to 2.25 will work, followed by prazi.