Make a stand for the cones. You can use an egg carton for this.
Cut or punch holes in the top of the carton to hold up the cones. Have an ice cream scoop ready and place the scoop in a mug of warm water. Remove the vanilla ice cream from the freezer and scoop out the ice cream and place firmly on the cones. Place them in the stand and return to the freezer to freeze for an hour to harden.
If you’re using all three kinds of chocolate, melt them separately. For this, first place the broken-up pieces of dark chocolate in a large heatproof bowl sitting over a saucepan of barely simmering water, making sure the bowl doesn't touch the water. Then, keeping the heat at its lowest, allow the chocolate to melt slowly – it will take about 5 minutes to become smooth and glossy. Then remove the chocolate from the heat, give it a good stir and let it cool while you repeat this process with the 2 other chocolates (the white and milk chocolates will take 3-4 minutes to melt). Next it's very important to allow each chocolate to cool completely to room temperature before coating the cones, or the ice cream will melt.
Set out the toppings or have them ready along with a spoon and a plate. Remove the ice cream filled cones from the freezer and then dip the cones in the chocolate coating the ice cream thoroughly. Allow any excess chocolate to drip off then quickly sprinkle the tops with the topping or sprinkles before the chocolate hardens.
Pop them back in the freezer until they are ready to serve. If you plan to make these in advance, wrap the cones in foil or parchment so they don’t pick up any aromas from other food stuffs from the freezer. After 2 hours, you'll find the chocolate will harden around the ice cream immediately.