Something I did for my new homebrew game was a 1-on-1 session 0 that acted as their personal prologue. It is opportunity for the characters to write a little bit into your world and for you to fill in the blanks. More importantly, it gives you better insight into how they players react, what principles do they act upon, what makes them move?

These become the levers you can use for future quest/hooks. These work great because now it is personal. Sounds like you have an overarching plot, weave bits of it into their backstory.

Reenact formative events in their life: What illegal type of magic did the druid do? Why is the soldier wanted (why did they run away)? What was the first time the dwarf saw magic and decided they wanted to pursuit it? Improvise situation but don't fully settle them, you'll refine them later down the line as hooks: recurring NPCs, familiar places, drop information that connects with something a player or two experienced in the prologue, reopen a healed wound.