What is the correct way to use the Zerostat?

Zerostats do not work. The problem is that as soon as the stylus starts rubbing the groove static electricity is generated pulling dust towards the record. There are two ways to deal with this. The first is always use a dust cover. If your table does not have one there are companies that will make one for you. You can hinge it to your cabinet.
Next is this  https://www.sleevecityusa.com/Antistatic-Record-Cleaning-Arm-p/tac-01.htm. I have used one version or another of this for 40 years. The bristles of this arm are conductive and its base is connected to ground. It dutifully follows the grove discharging the static and sweeping any incidental dust out of the way. If you have a good mat and a record weight you will not hear it at all. At the end of the side I give it a wipe with a standard felt record brush. I have never worn out a stylus .
You have to position the brush just right. Too close to the plater and it will skate inwards, too far and it will skate outwards. It should follow the record right along with the tonearm. It is terribly expensive at a whopping $20. As an aside, NEVER treat your records with any surface treatment. Last is a joke. It is just plain Freon! Nothing else in it. If you have some put a drop on a clean mirror and let it evaporate. Put another  drop in the same place and let it evaporate. You can do this a thousand times and you will not see a darn thing on that mirror. Nice scam. "Oh but it makes my records sound better!" Placebo. Anything that sticks to vinyl is going to gum up your stylus. The trick for keeping your records clean is don't let them get dirty in the first place. "oh but the record is loaded with all kinds of gunk from the factory!" My a--. Take a clean bright white cloth and spray it with a little distilled water. Wipe every new record you buy right out of the sleeve before you play it. Keep the cloth in a plastic bag. Wipe every new record you get for a year. What do you see on the cloth?
Anyone want to take a bet?  I do keep a Spin clean handy for when other people bring their records over or if I do something stupid like spill my coffee on the record.

Lewm You can contradict me all you want.
Zerostats will kill static VERY temporarily. Like I said before the stylus rubbing the groove puts the charge back on in a hurry attracting dust to the record and there is plenty of dust in the air just look into the beam of a flashlight in a darkened room. The static and incidental dust are the reason you need a grounded sweep arm. It kills the static as it is being made. There is absolutely no downside to using a dust cover. They keep dust off the record and your delicate tonearm and they also decrease the decibels around your cartridge, arm and record. 
If you have a complex table like a Basis or VPI it makes keeping the table clean much easier. I would never use a table without one. The myths perpetrated against dust covers were generated by manufacturers who could not easily attach one to their table or by people who have no idea what they are talking about. When humans have no idea what is going on
they make stuff up. They mythologize.  Zeus throwing lightening bolts is a good example. The mythology surrounding Audio is second to none. I have fallen for it on several occasions. 

Lewm,

The argument was not over the "dust bug" but over whether or not Zerostats work. If the goal is to keep Static and dust off the record they do not, particularly if you do not use a dust cover. If you use the Zerostat and quickly drop the stylus and shut a dust cover you will have less dust on the record during playback but you would have to use the Zerostat immediately on opening the dust cover to keep the dust from flying to it and messing up the next playback. If most people do not use a dust cover it is mainly because their table was not supplied with one not because there is some magic audiophile mythology not too. It is my contention that because the dust cover lowers the volume surrounding the cartridge and tone arm that tables with a properly mounted dust cover sound better. If you have an un suspended table you can not mount the dust cover to the table which is why all mass controlled tables do not have a dust cover. You have to mount the dust cover to whatever the table is sitting on which makes things a bit more tricky. But you can order your cover here  https://stereosquares.com/ and you can get hinges here
https://www.fullcompass.com  and with a little elbow grease, a drill and some cyanoacrylate you can have a really nice hinging dust cover. Put felt pads under the corners so it does not rattle. 

There is no correct way to use a Zerostat. The problem is once you start playing the record static builds up fast. The static charge is created by the stylus rubbing the groove. Even if you use a dust cover when you take the record back to it's sleeve it collects dust like a magnet. Hold a record you just played up to the light correctly and you can see the dust fly to the record. The only way to beat static electricity is to discharge the record while it is playing. So, if you don't want to stand over your record squeezing the trigger every 30 seconds the best solution is a conductive sweep arm like this one  https://www.sleevecityusa.com/Antistatic-Record-Cleaning-Arm-p/tac-01.htm. Also get rid of all your paper inner sleeves and get anti static plastic ones. Paper will hold a static charge.
Read about the triboelectric series here  https://www.school-for-champions.com/science/static_materials.htm#.XcFmJDNKiM8. You will notice that PVC is an electron magnet!