I don't know about etiquite...

but I would give the first few kids only a few pieces of candy and kind of judge how heavy the flow of trick-or-treaters will be... then you can give out more or less.... but two or three pieces of candy per kid is plenty. I hope you have fun... I don't think we will get any trick-or-treaters this year... cause we don't live in a neighborhood... I loooove to see the kids dressed up in their costumes.. they are so cute!!!... and too bad too cause I work at Nestle and they give us soooo much free candy!