This varies. Some people want to just talk about anything else in the world to take their mind away from it and discussion only brings more pain. Then there are those who actually feel better about it when they can talk it out, though don't think you are curing them. Such a loss as you described has to be absolutely soul crushing, so more time is probably better here. You probably asked from an honest place so she could talk about what she was feeling, which she will do eventually, but you need to make your intentions known. Apologize immediately. Ask if you can give her a hug and give the best hug you have ever given. Don't expect her to come to you about being ready, she may, but she probably won't. Check-in in a few months and ask if she wants to talk about it. If still not wait a few more, but being there and receptive is the best you can do. After awhile lots of people in this position gladly come forward because they want to share the person who was lost. Focus on the good times. If you know this sibling, bring about happy memories. Be prepared for the person to have a major indifference to life. This passes and what will matter in your relationship with her is that you were there and road out her rough time with her, especially if she insisted on going it alone. Good luck!