If you are a US citizen and at least 21 years old, you are eligible to petition to bring your brother or sister to live and work in the United States as permanent resident (green card holder). Once your petition for a brother or sister is approved, your relative must wait until a visa number is available before he or she can travel to the US
When your relative reaches the "front of the line," the US Department of State contacts your relative and invites him or her to apply for an immigrant visa. This process is referred to as "Consular Processing." After your brother or sister submits her application for an immigrant visa, the consular office will schedule him or her for an interview. Consular Processing can take several months, and your relative will not receive his or her visa until all the steps are completed. Once your sibling receives their visa, they may travel to the US and will receive their green card shortly after their arrival.
If your relative is inside the US when his visa number becomes available, he can apply to adjust status and remain in the US while his adjustment is pending. It may take several months for your relative to receive his or her green card after applying for an adjustment of status.
Only 65,000 visas may be issued to brothers and sisters of US citizens per year. Because of the numerical cap, there are long waiting periods to obtain a visa in this family immigration category.
China, India, the Philippines, and Mexico are countries with a high demand for US immigrant visas. Because US law limits the number of immigrant visas available by country, your brother or sister will have to wait longer if they are from those countries. Waiting times for brothers and sisters from China and India can be ten years or more. Waiting times for those from Mexico and the Philippines are often much longer.
Your brother or sister's place in line will be based on the date you file your petition. Therefore, you should file your green card application as soon as possible.