If you do want to make this ahead of time, you can make the balsamic reduction weeks ahead. You can also prepare the tomato mixture and set it in the fridge in an air-tight container for a few days. I would make it the night before, and then just toast the bread and assemble the bruschetta the next day.
Keyword baguette, balsamic reduction, balsamic vinegar, burrata, cherry tomatoes, crostini, garlic, olive oil, shallots