I would recommend working on both at the same time. Your form may change drastically but developing a feel for how to throw an anny, hyzer, hyzer flip, etc. will still retain its value regardless of how much your form changes. I made the mistake of only focusing on power while thinking... why should I practice these other things when my form is going to change anyway? In reality, learning the other shots will actually help to increase your distance because the other shots require timing, disc angle/orientation, footwork, etc.
It may also be a good idea to develop your sidearm. Its easier to learn both from the start rather than learn one and then years later start working on the other (kind of like learning a 2nd language).
Regarding the hyzer flip, generally you are trying to start out on a hyzer angle and put enough torque on the disc to have it flip flat and continue straight. With a lot of torque or a very understable disc, you can have it flip flat and continue to turn anhyzer. But for the purpose of learning, start by trying to get the disc to flip flat.
Summit - Panther - Roc - Super Stingray - Leopard - Teebird - SOLS - Wraith - PD - Tern