I'd be bored out of my mind if it took 2,000 in-game days (18 years at 28x4=112 days per year) to raise up a kid. I play on normal lifespan, aging off outside of played lots (for rotation reasons), and have a general rule about aging:
- Babies are aged up once they're Good Friends with both parents, using standard interactions with the crib
- Toddlers age up the hot minute they reach Lv5 in all toddler skills and Lv3 in potty
- Children and teens get their full life stage to rack up skill development and to get all the childhood aspirations plus all 9 scouting badges
- Once they're young adults, they go to college or move out on their own.
If that took forever and an age, it'd discourage me from doing it.