You can make the mini tart shells in advance and store in an airtight container until needed.
The lemon curd can also be prepared in advance and stored in the refrigerator for up to three weeks.
Before making the meringue, make sure that the mixing bowl, the whisk attachment or anything else that will touch the egg whites are very clean and dry, so no residual oil or fat is left behind to disturb or deflate it.
Store the lemon meringue tartlets in the refrigerator for up to 3 days.