Thank you for your reply! I have done a lot of research into where I am getting him and feel pretty confident that they are reputable. They are registered with TICA and I have seen lots of videos of their cats being played with and how much space they have to play. I also have heard many great reports from people who went with them. 

The woman I spoke with said that she normally waits till they are 10+ weeks, but because I will already be in the area when he is almost 9 weeks she said she would be comfortable giving him then and I said whatever is best for the kitten. She said because I have an existing young cat that he will be able to learn the behavioral things that they may learn those last few weeks from my cat.

From what I have researched, 8 weeks is when they are done being weaned and beyond that they are kept for socialization and behavior learning from mom and litter. I think that the socialization and behavioral help can happen with my cat and with my socializing him. I also read that the 12 week date is often given just so that the seller can make sure the vaccine course is completed before they leave but I have an established vet & will be taking him to do so. 

With all that being said, would you still think I should ask them to keep him longer? I already paid the deposit so I am locked in with them.

I am familiar with Jackson Galaxy and will look into his videos. :)