Sister's Room and Becoming a Big Brother

Our second baby is going to be a girl, and in just a few short days, Joshua is going to be a big brother. His world is going to turn upside down, and Joshua doesn't really know what he is in for at this time. He is 2 and knows about babies, but he doesn't understand about the baby in Mommy's belly. He also knows that the room next to his room is his sister's room. Every night when he comes upstairs to get ready for bed, he says "sister's room, sister's room" opens the door and walks in. He loves being in his sister's room, but he doesn't know what that means. Soon, he will really find out. We wanted to prepare him as much as we could, but since he is so young, he really doesn't understand. Once we come home with the baby, we will make a big deal out of Joshua becoming a big brother and how exciting it will be for him. We know that there are some struggles ahead but anything we can do to help him with the transition, we will do.