Absolutely! Ideally you want to let them set in the fridge for at least 2 hours before you slice them. This just allows everything to firm up, so they stay together when you slice them. You can definitely make them the day before and then slice to serve. I also slice them, and then place in individual containers for people to grab and go for lunches for 3-4 days. If you add ingredients like lettuce or tomato that can get soggy and change the texture you would want to avoid that.