Foster to adopt advice

I want to adopt a sibling group from the foster system, max 9 yrs. I plan on retiring at age 55 and want to focus next ten years raising them. The reason I want a sibling group is that I understand there is a higher need to keep them together and I will be an old mom so I realize at some point they will need to be each others family when I’m not here. I have a lot of experience with kids am single and have done a lot of healing work in my life so I understand it is a process healing from trauma. We have great supportive services in my county but I saw a sibling group that is out of state. I was wondering if you have any advice? Am II taking on too much with a sibling group? How does it work if I adopt outside of my county or out of state? How fast do you think I would get a placement, I am in Alameda county in ca. And I am just starting the process so curious how long it takes to get certified?