Can anyone advise on how long a cake would stay fresh?
I would make a red velvet cake with buttercream and probably covered in fondant. I would bake and finish the cake on Sunday, but it is not needed until THursday. I live in PA and someone can only pick it up on SUnday. Would it still be good?
Crazy I know...But help anyway...

as long as it's sealed so no air can hit the cake, you'd usually be good for up to 7 days. Make sure you use some simple syrup to guarantee it's moist when they eat it.

THank you ! When do you put the syrup on the cake, before you ice, decorate and wrap it up?

after you have split it, and before you put the filling in. Put a tablespoon or two on each layer with a pastry brush, mostly around the edges as they are more prone to drying out.

Thank you, how would you seal the cake, with saran wrap?? then boxed?

Just for fun I did a "test" about 6 years ago. I made a bunch of cupcakes and a small batch of BC (1.5 parts butter to 1 part Sweetex). I thickly crumbcoated the tops of the cupcakes and placed about a quart of BC in an airtight container. I left the cupcakes sitting in the counter - uncovered, and put the BC in the cabinet. I lived in the upper high desert in California and this was summer time. So we are talking extreme heat during the day (well over 115 - 120F) and sudden drops in temps at night (easily as low as 40F). No A/C or central heating in my house. Just a cooler and wood stove in the LR, nothing in the kitchen but open windows and fresh air. Results?

It was a full two weeks before the cupcakes started tasting even a little stale (but still tasted good). 3 weeks before they were stale.... not hard - just stale... still edible.

BC: 6 full months before it started separating. I stirred it, it kept it's semi-firm consistency and it tasted fine. It was about another three months later it got to where even when I stirred it, it would not mix back together.

So, that's how long this stuff stays fresh. Would I serve 3 week old cupcakes and 9 month old BC to customers? No. But that is the technical answer to your question.

A scratch cake can taste old as soon as three days. Banana cake tastes stronger every day, so that one only lasts two days. I have only a few that will keep a week, and that is in the winter in the garage.

I've never made a boxed cake in my life, niether has anyone I know, they are pretty much unheard of here. One baker I know said to me that her (scratch) cakes get better and better under the fondant. Maybe it depends on the type of cake *shrug*

angelmare, when I said 'sealed' I meant with icing. Then put in a box to protect from bugs, NOT in plastic as the fondant will go sticky and gross. The rest is up to you. Some people don't like putting cakes in the fridge, others are fine with it. While it's true that refrigerating your cake will change it slightly, it's your decision as to whether or not you want to. If it were only a day, I'd happily put it on the counter under a cake dome or in a box. But for several days, I think I'd prefer mine in the fridge. Again, totally up to you though.