Thanks for the question! That is a correct deduction, good job! The reason we can conclude this is because we know that P is earlier than G and S based on the second rule, and so G and S cannot be on the first day. But we’re also told that G and S can’t be on the 2nd and 3rd days, which we read directly off the third rule. And so that means that G & S are always going to be in spaces 4, 5, or 6.
Hope this helps! Feel free to ask any other questions that you might have.