I normally only decorate cakes for fun but I got asked to donate a cake to a charity auction and an order for 36 fondant disk topped cupcakes for a baby shower. I made the toppers about a week ago, still have a couple more to do and small details to add but I read they should have drying time so I hope I was right in doing that. I also baked all the cupcakes ahead of time and froze them. They are getting picked up Sat. at 9 a.m. I am wondering when I should thaw, frost, fill and add fondant toppers? I was thinking of frosting/filling them tonight and adding the toppers right before they are picked up but I don't want to have to refrigerate the cupcakes as I'm worried it will affect the flavor. The only filling I think might need to be keep refrigerated would be the lemon curd/cream filling?

For the auction cake I am making a two tiered girls birthday cake and she wants the bottom tier only to be filled with milk chocolate mousse. I am using the recipe from this site that uses egg whites. This cake is getting picked up Sunday morning and I want to have it done Saturday night but I don't wan to put it in the fridge, one it can't fit and two every time I put my fondant covered cakes in fridge or freezer they get condensation on them and it ruins my decorations. Does anyone know how long this mousse filled cake can sit out safely? I do have some rooms in the house that a very cool. Here is the mousse I'm referring to. Thanks so much in advance for your help.
http://cakecentral.com/recipes/chocolate-mousse-cream-filling/

Someone advice please!!

You can complete your cupcakes on Friday night. However due to the curd filling I would put them in the fridge when you finish. It should not impact the taste unless you have some strong smelling items in your fridge. However, I would put the topper on before they pick them up.

As far as the cake I am never a fan of leaving a cake out all night long contrary to what others may say on CC. I've never tried the mousse recipe you attached so not sure how stable it will be after leaving it out all night. Therefore, you may want to make both tiers of the cake, fill, frost, fondant and decorate but stack them in the morning. Perhaps that will give you the space you need in the fridge.

I personally don't think you need to worry about leaving your cake out overnight especially because you're using fondant. Fondant acts a bit like an insulator so if you put it in a cool room, you should be fine. I've left fondant cakes out overnight and haven't had any problems. Fondant is known to have condensation if you refrigerate it.

Thanks I got the cupcakes done and put them all in the fridge, tightly wrapped with plastic wrap. I used to always put my fondant covered, decorated cakes in the fridge/freezer but the last time some of the decorations were hand painted with food coloring gels and when the cake came to room temp the sweating made it run like crazy. Thankfully it was for my son's 1st Birthday and I had already taken pics. I'm trying to prevent anything from getting ruined by a sweating cake which is why I wanted to avoid refrigerating it after it was decorated, but I'm way to slow at decorating to wait to decorate until the day it is due to get picked up. Is there any way to prevent the cake from sweating? Thanks again for your help!

The only way I know to keep fondant from sweating is to keep it out of the fridge. You can make all of your decorations well in advance and apply them the day before your cake is due; leave it out overnight and then deliver it the next day.