Cut all the sides down to size. 5” tall, long sides are 13” and the ends are 7”, but they will be between the front and back, so the side will be 8” long total.
I only veneer the insides when I build a veneered box because when I cut the top free, I don’t want to lose the outside grain match to the saw kerf- inside isn’t noticeable and would be very difficult to glue in after the fact.
I will be assembling the sides with 4mm Dominoes.