Combine blueberries and 2 Tbsp. sugar in a bowl and mash about 1/4 of blueberries with a fork to release some juice.
Let stand, stirring once or twice, until sugar has dissolved, about 5 minutes.
Combine cream cheese, sour cream, remaining 1/4 cup sugar and vanilla in a large mixing bowl and beat with an electric mixer on medium-high speed until fluffy, about 3 minutes.
Spoon 2 Tbsp. of blueberry mixture into each of 4 parfait glasses. Top with a heaping tablespoonful of cream cheese mixture and 1/2 Tbsp. graham cracker crumbs. Repeat, layering, ending with graham cracker crumbs.
Serve immediately or cover and refrigerate for up to 8 hours before serving.
