if you are a one day old player, I would recommend rerolling to get the unit(s) you want, at least up to a point. Now is a particularly good time to do it since you’ll have an extra 15 orbs to pull with.
Who is the best unit to reroll for currently is tougher to say. All units get access to the hero fest banner for one week, so probably not any of them. Rerolling for a +atk harmonic veronica or pirate tibarn would definitely be a good choice. After that, I’d probably recommend pulling on the hero fest banner for 1-2 copies of each unit, their fodder is just that good. The rest of your orbs from the story I’d save until you see what cyl4 offers.
Also - when cyl4 drops in a week, you’ll lose your free pick from cyl2 soon after. So if you want three free heroes, make sure you choose one before then.