Hey! Hoping I can find some help here. It's been a while since I've been on here. 

I'm making the Groom's cake for my brother's wedding and I'm actually in the wedding as a bridesmaid. My 2 children are in the wedding and my husband is the best man. We're somewhat involved as you can see. We are getting a hotel to stay near the venue for the rehearsal on Friday and the wedding is on Saturday. For this reason I would bake the cake on Thursday and either completely finish it Thursday or finish it up on Friday. If I finish the cake on Thursday (likely) then the cake will be completed for 48 hours before the reception. The filling will be a Nutella filling. The icing is a basic chocolate buttercream recipe 50/50 butter/shortening. 

My question...

Is this even okay to do... ? 

How far is it from your home to the venue? 

We live approximately 45 minutes to an hour from the venue, which is the reason for the Friday hotel. The hotel is near the venue. 

How many servings and how complicated is the cake design?  And how experienced are you?  There are certainly a number of ways that you could successfully do this.  It is a grooms cake, not the wedding cake which takes some of the pressure off.  If it was me, I would do the whole thing ahead of time and freeze it. You could make it a week ahead of time then, or when it was convenient for you.  Take it from the freezer to your car for the trip and it will defrost well before the event.  Less stress for you, will be done ahead of time, will be fresher and yet you can do this for your brother.

Well, this is happening this Saturday. I'm experienced enough to know I can do it. I don't crank out weekly cakes by any means. I do decent work for my family and friends. Right now I believe the cake will be a 10 inch square 2-layer base with an 8-inch 2-layer on top. Iced in chocolate. Buttercream transfer on top.

I'm thinking now. There are a couple of routes I could take here. I've never freezed a fully iced and prepared cake. Would it make a difference between refrigerating vs freezing for one or two days time? 

I'm wondering if I can have someone pick up the cake from my house before the ceremony on Saturday. I don't think I could fit this in my freezer, but if it would hold up fine in the fridge, I could do that...? 

I could also just table the whole thing and there just won't be a Groom's cake. I don't want to serve something less than stellar :(

AI always bake my cakes 2 days ahead, i would not freeze it, but put in the fridge when done. Are you able to drop it off at the venue on Friday, before you go to the hotel? They could store it in the fridge and place it out for the reception. Hope it all works out.

It will be fine, just make it as you had planned.  Many event cakes are baked on Thursday for a Saturday event.  You will just need to figure out a safe place to store it until you set up at the wedding, wouldn't want a suitcase or something accidentally to squish it in the hotel room.  There is some controversy that refrigerating a cake makes it dry out, so it really depends on what side of that fence you are one.  But it will be fine at room temp also.