In case you've ever wondered, I keep a chart of where they are when and how old they are. It's the only way to keep track and avoid continuity errors!
I haven't quite reached halfway yet and more surprises are sure to come, but I'm anticipating that this one should be ready for release by late March/early April. I can't commit to a definite release date yet because the editing stage can be unpredictable.
The story is forming though and it has a structure. I hope my readers will enjoy it as much as I'm enjoying watching it develop!