Filling without a machine
Updated
Hand pouring is entirely viable to a few hundred candles a run, and the difference between neat and messy is two pieces of equipment.
A pouring pot, not a jug
A proper pouring pitcher with a narrow spout and a comfortable handle. A saucepan or a jug with a rolled edge dribbles down the outside and marks every vessel it passes over.
Two pots are better than one: melt in the second while the first is pouring, which roughly doubles throughput.
Set up first
Vessels wicked, warmed and lined up. Labels not yet on. Thermometer in the pot. Reserve for the second pour set aside.
Everything within reach before the wax is at temperature, because the pour window is the constraint and anything you have to go and fetch is spent out of it.
Working a batch
Pour in one continuous movement per vessel, down the wall or onto the wick bar rather than straight at the base.
Work at a steady pace and do not stop halfway. A pause of five minutes means the last vessels are poured at a different temperature from the first, which shows as different surfaces.
Check the pot temperature every few vessels rather than at the start only.
Cleaning as you go
Wax on the outside of a vessel sets hard and has to come off before labeling, because no label adheres over it.
Wipe while warm with dry paper. Cold it takes a fingernail, and fifty vessels of that is an hour nobody costed.
And never pour wax down a drain. It sets in the trap, which is an expensive lesson in a rented kitchen.