OMG im so nervous! I feel like I'm reallyl behind! i Have a 2 tiered cake due sundaymorning (tomorrow morning im in san diego ca).  I froze my cakes a few hours ago and i just removed them just a few minutes ago to thaw till morning cuz I read I shoud'nt freeze them before I add my bc. I'm really nervous about bulging.  I'm so so confused about when and how to have my cake settle? in 8hrs or so when its 8am I plan to unwrap my thawed/room temp cakes and fill them with bc.  I guess I should pipe a thick dam of bc around the edges of the cake, stack, and push down on the layers. Then what? Do I smooth out the sides then put in the freezer or dont smooth out the sides and still put in freezer? after that do I crumb coat, put back in the freezer, then add my fondant? I've read several different ways to have my cake settle. I also read to fill cakes and layer then put weights on it to push out the air? I'm really confused. Any suggestions? Sorry for all the misspelled words and run on sentences! Thank you! :)

ASince you said thick dam I'm assuming you're working with American powdered sugar buttercream.

Thick dam, fill, settle either by pressing down as Leah_s describes or placing a weight on the cake for say 30 minutes or so. Yes smooth down the BC (that squirts out) on the sides before placing in the refrigerator as you 'll have less chunks to deal with when you start to do your crumb coat. Don't forget to wrap the filled cakes with plastic wrap before refrigerating to settle/firm up. Then add your first coat, smooth, firm up (fridge/freezer, your choice), then final coat if a BC cake. If covering with fondant you can skip the second coat depending on how thick your crumb coat is, freeze till firm (maybe 10-15 minutes if using all butter BC) cover with fondant, and if your fillings don't need to be refrigerated you can leave out of the fridge. Some folks refrigerate their fondant cakes. It's up to you. Let the fondant set before you start to add decor or you could mark it.

All the cooling contribute to possible fondant bubbles (different from bulging). I've read to stick a coffee stirrer in a spot that will be covered with decorations to give the air pocket a way out if it forms.

Thank you for replying! So the top tiered cake I will be filling with a nutella buttercream and crumb coating it with ganache...the bottome tier will just be cream cheese frosting for both filling and crumb coat. Will that make any difference as to what you explained?
 

How come people talk about settling thier cake over night or several hours? I don't have much time just today. :(

AYes, Cream cheese changes everything. Not to alarm you but cream cheese BC and fondant aren't really great friends, they typically don't play nice together. Cream cheese also needs to be refrigerated throughout your decorating process for food safety.

Your ganached cake (using standard ratios of 2:1 chocolate to cream for dark, or 3:1 for milk/white)however can sit on the counter till firm (typically overnight) and then you can cover with fondant and keep on the counter.

You don't have to wait 8 hours for your cakes to defrost, usually all it takes for single 1-2 inch layers to defrost is less than 1 hour or so... if you don't stack them on top of each other. So you could cover them, go to bed and fondant in the morning.

People have time to settle their cakes because they anticipate the steps and plan accordingly. Once you do a couple you kinda know how long it takes to do what; so you know when to begin.

I never press down or place a weight on my cakes. Haven't had a bulging cake in 30 years. I fill and crumbcoat and leave in fridge overnight or a few hours. Then top with buttercream and/or fondant. I've never understood all the extra steps. Since cream cheese frosting is not really stiff as buttercream, I would make a buttercream dam on that one as well as any cakes with filling other than buttercream. I also refrigerate all my finished cakes and to my knowledge have never had air bubbles in fondant or buttercream. 

A

This makes sense since per your description, you cakes are cool all the way through and after the decorating process. For folks who do the back and forth between cool and room temp, the possibility of air bubbles increases as cool air expands.

For my SMBC cakes that are cool from beginning to end of the decorating process, I don't weigh them down or press down. But when I use ganache where I don't keep the cake cold, I have to consider the possibilities as my cool cake must now come to room temp and stay there.

Different strokes for different folks. I guess OP'll just have to see which method works for him/her.

P.S. You are so blessed to not have to deal with those pesky bulges.