Melting table salt with sand

you will end up gassing yourself because "salt glaze" pottery is done this way and the studio gets filled with dissociated chlorine gas. BE CAREFUL. (PS, Id throw some powdered Na feldspar (called SPAR in steel making) to help initiate it all.

Yeah I was aware of the danger, but at about what temperature will this occur? Will the salt act as a sort of flux?

I think itll dissociate at cone 1 (I forget the exact temps). Since Quartz needs to be at roughly 800C and 700C with flux. I think the Cl will dissociate. Use an elect kiln and keep the windows open an use a timer so you can reenter the room (Unless you have a shop outside)
Remember, Cl is the best oxidizing agent we know, and youre gonna be generating it.

Think of the painting by John Singer Sargent called "Gassed", where this line of gassed WWI troops are being led away. Cl is as lethal as mustard gas and phosgene and itll burn your eyes and youll be blind.

I always like to scare my students in lab.

Thanks for the warnings, I know chroline is very dangerous (just recently and accidentally opened a container and got blasted lol).

I work outside with mud kilns and my own charcoal, so I guess I can avoid most of the danger.

You know of any other, easy to come by compounds I can use as quartz flux?

You can use pirrsonite , ntron, an even some of the low Ca/Mg feldspars.
High Ca feldspars can be difficult melting with ilica but they create some neat color iridescence and "chatoyancies" Look up ANORTHITE gems and check the images, youll see that it seems to glow like opal.