How do you explain waiting times to a 3 year old?

And specially, time such this as waiting for your brother who is on the other side of the world, waiting to be reunited with us?

This waiting part has been so hard and difficult for all of us involved. It has been 4 months since I saw Nathan's face for the first time. Never for a moment doubting that he will become my son one day. However, the waiting part has been hard on Emily too. She is just 3 years old and does not understand the word "waiting" to its full significance.

Let me explain it.

On one occasion, she saw how the big brother of one of her classmates came and pick him up. Her classmate, "J" was so excited to see his brother and without knowing, transmitted this emotion to my little girl. She just stood there in awe, glaring at them with wide open eyes for the longest time, as they embraced in a big hug, following by greetings of love and camaraderie. She took it all in and on our way back to the car, showed me her deepest emotions. She asked in a very soft voice, where her brother is, why wasn't he ready yet for us to go to China and get him and why we have to keep waiting and waiting and waiting. Her face was very sad and she had a thousand more questions all over her little face. Questions that I did not have answers at that moment, at least not the ones she wanted to hear. I wrapped her in my arms and explain the best I could. She was very silent on our car ride home, trying to process what she just witnessed and realizing that the waiting part will still be there no matter how I tried to decode it. We all hope and pray that the waiting will be less each day, that someone is preparing Nathan's heart, to the best of their knowledge, what is like to be part of a family with a mom, a dad and a sister, who is anxiously waiting for him to come home.

So I ask, how do you explain waiting times to a 3 year old?