I used a 6cm round cutter which gave me 10 good sized scones.
Try to handle the dough as little as possible ... this will help stop the development of gluten which can give you a dense scone ... which is not what we are aiming for.
When cutting into the scone with your cutter, press directly down into the dough ... do not twist the cutter as that can "mess" the sides of the dough together which can inhibit the rising of the scones.
As you brush the tops of the scones with egg, try not to let the egg drip down the sides of the scones as that can also stop the scones from where where the egg has dripped.
Scones are best served warm on the day they are made, but can also be lightly warmed through in the oven the next day, or if you are like me I like to cut them in half and toast them in the sandwich toaster which gives them a gorgeous crust.