Well, first of all, I woulnd't give any nuts to a pre-school child unless under strict, close supervision: and certainly only one variety at a time, so that if they do have a reaction, you know exactly what it is Many children have nut allergies, which, put bluntly, can kill.
And I've never heard of needing a particular time of day to eat these foods - and raisins are a fruit, not a nut or a seed.