When should I make Marshmallow Crispy Squares for gift?

[LadyMaybe]

These are from Nigella's 'Express' book, and look simple enough for DS (3.9) to help me. They're just rice krispie squares made with marshmallow and edible glitter so they look very pretty. It's just I've never actually made rice krispie squares so don't know how they behave!
If I made them Thursday do you think they'd go sticky/soft by Christmas day or would they be ok? Her recipe doesn't give any guide to storage so I was planning on just using an airtight container to transport to parents' place on Christmas Eve day and transferring into the 'festive' gift box that evening.
Could wait until Friday I suppose but would like to get things off my freaking enormous list done

Oh I don't know but you couldn't do me a favour and post the recipe here could you?

Ok but someone has to answer the timing question in return, deal?

45g butter
300g mini marshmallows
180g Rice Krispies
edible glitter or sprinkles (opt)

1. Melt the butter in a large, heavy-based saucepan over a low heat.
2. Add the marshmallows and cook gently until all melted and blended, stir constantly.
3. Take off heat and add the cereal, mix lightly until all coated.
4. Press into greased 32x23cm tin. Might need to use gloves and press down as will be v sticky. Flatten top and sprinkle with glitter or sprinkles.
5. Let cool completely in the tin, then cut into 24 squares.

Picture shows them with little candles inserted into some which makes the glitter sparkle.

From - Nigella Express, published by Chatto & Windus. Copyright is Nigella's of course.

I've made the Kellogs version of these and they kept fine for several days. Although how they lasted several days in this house;-) It's the most incredibly sicky tacky mixture I've ever made, quite hard to work with. Would recommend you cover with cling when pressing into the tin and leave the cling in place until fully chilled and set.

They should be fine in an airtight container for a few days!