First of all, congratulations on getting such a great fighter!
As for the blocking, I can't say I have much experience with well timed blocks but I usually need to when I use Double and I don't want her element to change. You're kind of a sitting duck until the opponent charges you. Be especially wary of fighters that have a lot of projectile special moves like peacock and Parasoul, I wouldn't even bother trying to perfectly block those. So just make sure to keep an eye on their special move availability when you fight them. However, once any opponent charges you, try blocking right before they hit. It may take some practice and getting to know the AI, but it's not a bad starting strategy. Do be cautious of Big Band too, he may try something while charging and you don't want to accidentally hit him instead of block.
Hopefully this was at least a little helpful to you! Unfortunately I don't have a fighter that needs perfect block to work and the Devs haven't really specified what that even means but it couldn't hurt to give this a try and see what happens! Best of luck!
With Feathered Edges Fukua, she can join Hack n' Splash Ms. Fortune and Star-Crossed Parasoul for Team Perfect Block.
Best way to learn the timing is on the battlefield. Either in Prize Fights or if you want no risk, go to the Daily Events. You can always bring a strong teammate along just in case Fukua falls.
Like HalloweenQueen said, becoming vulnerable like a Double that doesn't want to change element is key. You have to get used to the dangerous "letting go" stance of anticipating the attack so you can block at the last moment. This also includes back dashing and other methods to cancel your character from trotting forward.
I've been using Star-Crossed a lot and I noticed that I could activate her ability by ground combo (do not finish the combo) > back dash > block. If the opponent chased you during the backdash and attacks you, it seems to count as a well-timed block.