Honestly, I'd say don't keep trying to cork until you can 360 and 540 with ease.
Corks are easier to throw because they don't require carving, you can literally just thrown your shoulder towards your knee and cork 540, but they're also more dangerous if you haven't learnt proper rotation yet.
A few things if you still want to learn corks before normal flat spins (I'd advise against it):
1) You HAVE to spot the landing
Because of how corks are spun, if you don't spot the landing it's easy to rotate past the first corked axis and end up landing sideways or upside down.
You need to focus on when the landing comes into view and focus on spotting that landing to make sure you can stop the rotation or speed up/slow down the rotation to land the right way up.
2) Don't just huck corks
As I mentioned earlier, corks are insanely easy to do. However, you need a certain amount of skill to determine how hard to throw that shoulder into your back leg/knee.
Part of becoming good at corking is knowing how hard to throw a cork 540 on a 20 foot jump vs. a 40 foot jump because the speed of the cork has to be different if you want to end up landing the right way up.
This is one part learning about how hard to throw your shoulder into your knee and one part spotting the landing to help with controlling the rotation.
Corks are all about knowing where you are in the spin, which again is why they're typically best left until after learning 360s and 540s because there are certain aerial skills you'll pick up learning 360s/540s that you'll need for landing smooth corks.
For example, if I'm doing a cork 540, I can do a flat 540 first to have a rough idea of how hard I need to spin to get a cork 540 around perfectly on the jump.
If I don't have that I'm literally just guessing how hard to throw the cork, which is bad because you can easily end up landing upside down, especially if you aren't used to spotting the landing.