My mother just got recently approved to migrate to the US as LPR. I am a USC. Now I was wondering how soon my mom can submit a petition for my brother who is unmarried and over 21. I am assuming it would be faster for my LPR mother to petition my brother than me.
It will be faster for her to petition and she can do so as soon as she wants. I would suggest she should apply when she moves to USA. If you wish, you can also start a petition for your brother. He can wait in more than one category.