Even if it’s a working title, unlikely to remain, just give it a name.
It’s like having a kid – you kind of need to have something to call it. “Hey, you”, “WiP” or “That thing that’s tormenting me constantly” (hey, just like a kid!) just doesn’t cut it.
“I don’t want to give it a name until it’s finished” … that’s like waiting until your kid presents a personality before you name her/him … on the 34th birthday you can yell “Hey! He’s a Norbert! Norbert, your years of being Number 5 are over. Congrats!”
Giving it a name, a title, makes it real, crystalises it, makes it something serious – it makes you take yourself seriously as a writer.
So. Give it a name, even it it’s Hal.