If you have a ripe fruit, then there's no point in soaking it in orange juice (That's what the OJ is trying to replicate.) Some people recommend planting the seed in it's own pulp. And yes, bottom heat is likely to speed up the process. And the sooner you plant them the better.

I ended up soaking them in OJ overnight and planted them yesterday. I wasn't sure whether to cover the pot with plastic or not, I did. Was that a bad idea?

You're fine- don't need the plastic, but if you leave it on nothing bad will happen.

Seeds should be planted deep enough they don't really need a high humidity at the tippy top of the soil (that's what the plastic does) so plastic or not doesn't really matter.

Just *Do Not* let the soil get bone dry. Moist = good. Wet = bad. Dry also bad.

I have them on a seed mat and did end up removing the plastic because there was so much condensation I was afraid it would stay too wet. I'm just misting the soil now. How long does it usually take a violetta seed to germinate? Should I rephrase that to ask if they haven't come up within X amount of time should I give up? lol
Karyn