It depends on how the child handles things. People don’t break things down the same way. Where some may be able to start moving beyond the trauma, others hold on to it and fail to progress. It’s not reasonable really to assume anything, in my opinion. It’s such an individual response, you really never know, until you see how they handle the situation. (or don’t handle the situation.)
You can help the child, in many ways. Provide an outlet to discuss the trauma or the emotions attached to the trauma. Other play therapies are great – color, play-dough. Also, a licensed child therapist is a good path to take.
Don’t force the conversations, but reassure the child that they can talk to you. One thing I was taught, put something – like play-dough in a child’s hands and conversations can flow, without them really focusing on the conversation to the point where they won’t talk about things.
@Macaulay – I was young when my biological father was murdered. For a very long time, I couldn’t sleep without hearing the scream my mom let out when the police came to the door. I remember the rain, the words and the look on her face. Children remember things. Some may not, some do – very vividly.