Unfortunately, there is no concise answer as to how long it will take for your child or any child who was adopted to adjust to their new lifestyle. This process often hinges the circumstances under which your child was adopted as well as the age of your child. It will also depend on the bonding experiences they are being offered and the past experiences of the child. There are many things you can do to help them adjust and create an atmosphere of trust. However, the adjustment period will last as long as it takes for the child to feel comfortable and safe in their new environment.
It is important to acknowledge that your child is coming into your home with a lifetime of experiences. They have years of different people and parenting styles. They may have incredibly different ideas of what a family is and what their role is to be within that family. It will be a learning curve for everyone in the family. Lay out the expectations for your child, but also spend a significant amount of time showing them what family means to you. They will only know their role through time and experience. By acknowledging that you are all learning, there can be a general understanding of a need for communication.
Routine will be very important when you bring your child home. It is easy to want to have a sort of “honeymoon” stage for your new child. The tendency to want them to feel welcome and accommodated will be very strong. However, this can set an unrealistic precedent. Part of helping your child adjust will lie in showing them what the day to day will be like for them immediately. This will also help them to sort out where they fit within your family unit. When they are functioning as a part of this unit, it will help them to understand that they are home for good.
There is a very real chance that your older adopted child is experiencing some level of Reactive Attachment Disorder. They have gone through so much at such a young age and stability is not always their normal. It will be very much like learning how to live in a different country. Patience will be everything for your child. Understand that adjustments will not happen overnight. Provide resources such as counseling if needed. Counseling can make all the difference. It may take longer than you ever could have imagined. Be there as a source of stability in your child’s life. Once they see that you are not going anywhere and that you are not giving up, they will begin to ease into their new life.