I don't particularly like the name Jovanne and I feel like it would be strange for readers to have to repeatedly keep reading it.
I'd hazard to guess that if you, the author writing this character, don't particularly like the character's name, and you feel like the audience won't either, you should change it to a name that you do like. Possibly you have some kind of constraints relating to worldbuilding or the way that characters are named in your world, but even then, you are the author. You can exercise full creative freedom to make your character's name more enjoyable to you and easier on the page. Simply changing the name is the easiest solution to making the character's name less of a hassle for you and the reader.
However, if you do really want to keep the name, using a nickname is perfectly reasonable. Just make sure you spend a sentence or two clearly connecting the nickname to the full name, before you then refer to them by that nickname going forward. It allows the reader to make the connection of "okay, this character has that nickname" and prevents the potential confusion of "wait, who is this JD guy who just showed up?"
For example, if I have a character named something a bit unwieldy like "Nicholaus" and I would rather refer to him by the nickname "Nick" in the story, I would throw in an establishing line that points out the nickname so it fits cleanly into the rest of the narrative.
Nicholaus - or, as he preferred it, Nick - had that special kind of romantic track record that a bookie would call "so far against the chalk that it falls off the board." Most people, in fact, thought Nick must have been born with a wrench jammed into the part of his brain that allowed him to communicate with attractive people of either gender.
However, some names don't really need pointing out. "Ally" is a very common and accepted nickname for "Allison," for example, and "Rick" is a common alias for "Richard," so that kind of nickname doesn't necessarily need the same callout.