To Pahdz point, all I ever did when my kids were first starting was help them figure out where to stand and that they had both hands on the club, right below left.
As far as the baseball grip goes, at that age in particular, using all 10 fingers can simply help them maintain control of the club better than an overlap or interlocking grip can because their hands are so weak. Children, seniors, and women can all potentially see more benefit than problems from it.
And fwiw, there have been PGA and LPGA players that use a 10 finger grip (and still do). That grip will not preclude someone from being a very good golfer. Beth Daniel, LPGA Hall of Famer, used a 10 finger grip. Harvey Penick advocated it for certain folks in one of his books, and Jimmy Demaret always said he would have switched to it if he had to start all over again. It's fairly rare at the elite professional level, but it is not anywhere near the top of the list of things I'd worry about at this point.