NEED ADVICE!!

Hi everyone...my best friend is pregnant and wants me to adopt him or her. My question is, does anyone know about how this would work? Like, what are the Oklahoma laws about this sorta thing? would it be a bit cheaper in price since it's basically "direct placement" Also, can the paperwork for the adoption all be signed and legalized before she gives birth, or do we all have to wait until the baby is born. If we have to wait until the birth, does she have a certain amount of time after the papers are signed to change her mind and keep the baby? will I have to take classes? Will I have to do DHS visits? Also I currently stay with my mom's but can have the money to move in 8months, would they look down at that or would it be as long as you have it in time for the baby kinda thing??

TIA😘😘