You just have to progress the game, it will give you a prompt to go to the building once its ready. If its the standard option of visiting the building from your home its not ready yet.
Obviously 'progress the game' isn't very detailed, but the building is very late game for the current content.
Just concentrate on developing the the girls you have. I can't remember exactly but i think you need to get as far as you can with the mom content, then have a building meeting with the resident, then meet with the councillor, then organise a protest.
The game is very linear, but its also not very clear what you have to do to move each section on other than grind.. Hardly anything involves leaving your house. Just keep grinding the girl scenes until it stated no more content is available or you've trained them as far you can in each aspect.
For the most part you can wake up see if there any new mail/events from the new day screen, train a girl in the morning, wait a few hours train a girl in the evening, sleep. repeat.
The new content could pretty much be a straight VN, its severely lacking in UX