Cute cookies. NFSC dough as well as the cookies themselves freeze well. I would double wrap in plastic and ziplock to protect from freezer odors. Same for the cake layers. If you will "prefreeze" the cake you can stack to save on freezer space. Most buttercreams and fillings will also freeze well if placed in containers with tight fitting lids. Be sure to stir to recombine before using . I have no clue about freezing RI but it does keep in the fridge for weeks (store in glass to protect from breaking down). You didn't mention fondant or gumpaste, those both store great, tightly wrapped in a cool, dark place. Put the boxes together and store in pillowcases or closed boxes to protect from dust. So all of your prep can be done in advance. I would start with the cookies (already baked, set out to defrost Tues nite, don't forget to set out the RI as well) on Wednesday, 40 shouldn't take more than a few hours. Set the cake layers out to defrost that nite and start the cakes on Thursday...(again) use the assembly line...level, fill, CC and ice. I suggest you use fillings and icings that don't require refrigeration unless you have a walk in cooler at your disposal. Friday decorate and box. You didn't mention if the cakes were BC or fondant and what sort of decos you had to do...so HTH.
Oops guess I should have included that info. She wants both the cakes and cookies done with buttercream...no fondant. A simple little pink gumpaste flower on top of both.
Here's the timeline I would use. As early as I could I would assemble the boxes and store them. Then I would start 3-4 weeks ahead of time baking the cakes and cookies and freezing them. Then about a week ahead of time I'd assemble all of the cookies and then that last week I would work on the cakes.