There aren't a lot of options anymore now that USAA sold out its member's investments to third parties. You used to be able to move money between your accounts easily, with the only limit being the time it took for your funds to settle (a few days) and then same-day transfer to checking.
Any third-party options (i.e. Vanguard/Charles Schwab) will require you to settle, then do a funds transfer to USAA taking however long that ends up taking. You end up needing a business week or slightly longer to move money in and out of your USAA accounts.