Welcome to the Wefugees Community and thank you for your question.
People who applied for asylum in Germany will usually be obliged to stay in a so-called "Erstaufnahmeeinrichtung" - a reception centre/camp. The length of the stay may be up to 18 months (for singles, not families!) - for people with an "inadmissible" or "oviously unfounded" rejection of their asylum application (applicants from so-called "safe countries of origin", for instance), this period can be also up to 24 months.
I am afraid that you most probably can not move in with your brother immediately after your asylum application.
Would you agree or is there anything you would like to add dear @mbeon-fardeen?
In any case, please don't hesitate to get back to us with any further questions.
All the best,