I have up to 9 days to think about it, since Coinbase won't let me withdraw until the payment settles, which they said up to 9 days.

Are there any advantages to keeping bitcoin in Coinbase? Or is it more advantageous to move into a private wallet controlled only by myself (such as Samouri Wallet)?

Another concern I have is how fees would work and when is the optimal time to withdraw to a private wallet.