Another thought, you want your booth to look well stocked in the afternoon of the 2nd show, not picked over. I want to finish a show with it looking good, even if lots of inventory has been sold. I take double what I think I will sell and usually sell half of whatever is in the booth.
What John says, don't think in terms of these 2 days, just make inventory as if it was your daily job. Then you are not only prepared for these 2 shows, but can take advantage of other opportunities before fall.
You don't want to turn down sales this spring and summer because you are 'saving inventory ' for the fall, that does not make good business sense.