My oldest two went out a week apart. Both had already been gone to BYU so it wasn't a big change. It is rough when they are going through tough times on the mission though. The growth that happens and maturity and most importantly gospel experience and testimony makes it all worth it. It's especially fun when they lose themselves in the work and call home excited to share an experience with the family.
We'll get the first back in December and the other next summer. I promise there are good times ahead!