How large should a pad be for a 5mm screw terminal block?
What I always done in this case is put the pad size the double of diameter of the hole.

For example if the hole of the connector is with 1.3mm, the hole I put with 2.6mm of diameter.



If you put put a very large pad, you will have problems to solder the connector and could have cold solder too.

If you put a very thin pad the connector can be easily pulled, even when you're screwing a cable in conector.

So I recomend the double of the hole diameter when the datasheet doesn't gives you the pad size.