I was going to make a 3 tier cake for my mom's 75th birthday and I was thinking about making/filling the 3 layers on Wednesday to be served on Saturday.

There will be 3 layers - white velvet with a fruit custard filling, red velvet with cream cheese filling and German chocolate with coconut, pecan filling.  It will be buttercream sealed.

I'm not sure if it would keep until Saturday in the refridgerator.  I'm new to all cake making so I thought I'd ask the experts if this would be OK.

Thanks in advance for all the advice!

once the cake is entirely enrobed in butter, it should be fine. if you want to be extra sure about tenderness then you can use a simple syrup to drizzle over each layer before frosting. be sure to box or wrap the cake after it is cold so that the other flavors of the refigerator don't  seep into your frosting. 

Awesome!!  Thank you!