Yes, with some caution. You’ll want to mix the simple syrup and bourbon together in the same 1:2 ratio as in the recipe.  Put that in a large pitcher and leave on the bar or in the fridge.  When it’s time to make a drink, muddle the mint in each glass, fill the glass part way with the bourbon mixture, top with crushed ice and garnish with a mint sprig.   Please don’t add the ice to the pitcher or you will end up with very watery mint julep’s that won’t taste good at all. You also want to muddle the mint fresh for each drink so as to get the most flavor and aroma out of the leaves as possible.