Every single time I've seen this exact bug reported (the crystal ball saying 'explore the mansion' before the player gets in for the first time), people were using a mod. And the gallery unlocker IS a mod. So first, delete the gallery unlocker, it will probably cause even more issues in the long run. After all, the game is coded to be played, not cheated: the gallery unlocker messes with the variables to let you watch the scenes from the crystal ball, meaning it breaks the actual gameflow.
After the date with Simone in which you learn about her chastity belt, there's another date with her at the wall at night (you can go there either at night or late at night) and she gives you the passage permits... and some other present. Maybe try to go there at that time, don't wait at the wall clicking on the clock. Then everything is railroaded until the actual 'explore the mansion' hint. Here's a 0.4 save in case you can't go back to a clean point of your game (you'll need to start over Simmone's quest and of course Rose's), it will show up on page 8 of the load menu