Laura is correct. I'm afraid that open house submissions generally take 24 hours for our system to process. It's thus best if you can load them a few days ahead of time.
I'm sorry for the confusion and the inconvenience this may have caused you. Please let us know if you have any other questions or feedback to share with us.
It sometimes takes the Trulia site more than 24 hours to update a listing; including Open House times. I posted an Open House time earlier this week for one of my listings and it took Trulia 2 days for it to appear on the site.
I suggest that you contact them about it. You can call them at 415-748-3700.
Prudential Connecticut Realty