I think this is made fresh right before serving. Thankfully it is a simple and easy recipe to bring together that doesn't require a ton of time. If wanting to try and save even more time and prep ahead, combine the blueberries, sugar, and lime in a bowl. Wrap tightly in a bowl with plastic wrap and store in the fridge for 24 hours before using. Same for the batter. Mix together and wrap tightly, storing in the fridge for 24 hours before needed. Proceed with the recipe as follows when ready to bake.