I consider it impossible to give even a vague percentage, as I have no idea how long some steps will take and what problems I'll encounter. :D But here is a status post I made on discord a few days ago, maybe that'll help you to get an idea:
Status of the warmap battle changes:
Quite a few things still need to be done, but the visuals and core systems are mostly ready. That's why, despite the big amount of unfinished parts in this list, the system is already on a good way.
I plan to finish all features with the 6 first squad leaders for the next update, and then add the remaining characters in the next update. This should also help to prevent connected bugs from copying events.
- New overview for all squads, with changeable weapons, armor, horses, and upgrades you can buy for them: Done (for the first 6 squad leaders - See screenshot)
- Movement system: Now supports up to 5 AP, and you can walk multiple times without the blue tiles disappearing (as long as you have APs left)
- Check for enemies: Done
- Damage calculation: Partly done. A simple version for testing works, but now I have to add all bonuses and special effects.
- Deal damage and animation: Not done.
- Heal spells: Not done.
- New stats for all squads: Done.
- Visuals for the new squad leaders: Not done. I made temporary character sprites and face images for testing, but they'll get replaced once the CGs are done.
- New events to introduce the battle system and the squad leaders: Not done.
- Experience system: Not done. Level-ups will increase the stats of the squad and fully heal it.
- Abilities for squads: Not done.
- Usable items: Not done.
- Chests and loot drops: Not done.
- Turn end to refresh AP and enemy action: Not done.
- Auto-Heal after battle: Not done.
- New map start/win/lose events: Not done.
- Change to overview map for the battles: I'll most likely remove the troops moving to the battle for some turns, and instead make all battles start instantly. When starting the battle, you can pick a difficulty, which will tell you an estimated level which you need to beat it. This choice will affect the stats of the enemies in the battle.
- Destroyable barricades: Not done.
- Probably a dozen more things that I forgot: Not done.
About children: You can flag women as pregnant, but that doesn't affect anything yet. My plan is to show the pregnancy and children during and after the time skip event in the main story. But since I need to finish everything in the "current time" first, before starting with the time skip, it'll still take a very long time before children will be made. And since you can have a lot of children, it'll most likely take a long time to make them all as well. XD