My wife and I celebrated 6 months with our kids on May 1st, so we are relatively new at this ourselves. If you are looking to adopt a sibling group, God bless you, and get ready. It has been a more earthshaking experience than either my wife or I could have imagined. But, it is totally worth it. We have 3 kids, ages 9, 6, and 14 months. The older two moved in November 1. The baby moved in at the end of January.
Just a few comments about our experiences: when our kids (especially our oldest son) moved in, they were very very angry and did not have the emotional, spiritual, and mental tools to express that anger effectively. So, for the first month and a half or so, we thought we had taken in the children from hell. We seriously wondered whether we were doing the right thing or whether we had taken on a commitment that was more than we could handle. In time, things smoothed out, both in our children's behavior and in my wife's and my ability to effectively care for them.
Part of our problem was the naivety of our expectations. We thought "all you need is love" and didn't really realize that along with genuine love comes a large dose of patience, kindness, gentleness, and self-control (as well as the rest of the fruit of the Spirit). There are those moments where you just want to scream at the top of your lungs, but you know that what your child needs is a gentle redirection and a reassuring hug. Love means choosing the latter, even when it hurts (and God knows I have not always done that with my kids).
One thing that we did right was to learn as much as we could before the kids came to live with us. Our adoption worker had recommended The Connected Child by Karyn Purvis, and I found that much of what I learned from the book was what got me through those first few very difficult weeks.
My prayers are with you in this process. It is difficult, but rewarding, and you have my encouragement.