Most Helpful Guy
Just start getting closer. Even without dates. Go out for lunch, coffee, drinks, etc.
A couple weeks might be enough. But, be there for her in the meantime. That'll help her feel protected and will reduce the urge of sleeping with a random guy cause for depression
Most Helpful Girl
Ask her on a casual date (coffee etc that can be both a friendly thing or a date) and see how she reacts to you being flirty. Positive - ask her on a real date, negative - stick to being friendltly and date other people.