The perfect table size is up for debate 
There are many threads here where you’ll find similar varying approaches and answers
For the machine footprint 48x48 is about the smallest you want to make, it can be smaller but then you’ll have the stepper motors extending beyond the table surface. Since you want to put the controller on top of the table as well you would add 8 inches in the X direction for a table 56 inches wide and 48 inches deep.