It's great that you're going to make them! They are too delicious.

BTW...though I've never served them this way, I just got the inspiration, if you like sour cream, they would be dynamite with sour cream and scallions or chives.
I wouldn't make ithem that much in advance because of the oxidation. You can cut the potatoes a bit in advance if you leave them in a bowl with the onions, but not for too long.
My Mom used to make the following but I never caught her recipe and found this one, which is better.
Ok

Rugelach ... a delicious pastry, I actually use this recipe from Ina Gardner, the Barefoot Contessa...it rocks! The pastry is ever so rich as it's made with cream cheese and it's a dream to work with.
Rugelach
Prep Time:
10 min
Inactive Prep Time:
1 hr 30 min
Cook Time:
15 min
Level:
Easy
Serves:
4 dozen cookies
Ingredients
* 8 ounces cream cheese, at room temperature
* 1/2-pound unsalted butter, at room temperature
* 1/4 cup granulated sugar plus 9 tablespoons
* 1/4 teaspoon kosher salt
* 1 teaspoon pure vanilla extract
* 2 cups all-purpose flour
* 1/4 cup light brown sugar, packed
* 1 1/2 teaspoons ground cinnamon
* 3/4 cup raisins
* 1 cup walnuts, finely chopped
* 1/2 cup apricot preserves, pureed in a food processor
* 1 egg beaten with 1 tablespoon milk, for egg wash
Directions
Cream the cheese and butter in the bowl of an electric mixer fitted with the paddle attachment until light. Add 1/4 cup granulated sugar, the salt, and vanilla. With the mixer on low speed, add the flour and mix until just combined. Dump the dough out onto a well-floured board and roll it into a ball. Cut the ball in quarters, wrap each piece in plastic, and refrigerate for 1 hour.
To make the filling, combine 6 tablespoons of granulated sugar, the brown sugar, 1/2 teaspoon cinnamon, the raisins, and walnuts.
On a well-floured board, roll each ball of dough into a 9-inch circle. Spread the dough with 2 tablespoons apricot preserves and sprinkle with 1/2 cup of the filling. Press the filling lightly into the dough. Cut the circle into 12 equal wedges—cutting the whole circle in quarters, then each quarter into thirds. Starting with the wide edge, roll up each wedge. Place the cookies, points tucked under, on a baking sheet lined with parchment paper. Chill for 30 minutes.
Preheat the oven to 350 degrees F.
Brush each cookie with the egg wash. Combine 3 tablespoons granulated sugar and 1 teaspoon cinnamon and sprinkle on the cookies. Bake for 15 to 20 minutes, until lightly browned. Remove to a wire rack and let cool.