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My problem with it is that the lathe is very slow to stop. When I turn
the lathe off, it takes a few revolutions for it to stop. There is no
automatic way to stop, like on a lathe that I practiced on 18 years
ago. So my threading bit can end up anywhere.
What is the standard approach to this problem.
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Standard US practice is to simultaneously withdraw the tool using
the cross slide and snap the half nut out of engagement with the
lead screw. This required a good deal of practice and
concentration.

The longitudinal slide is then cranked back to the starting
position, the cross slide cranked back to its starting position
[a thread stop is very hand here] and the cut deepened with the
compound [top slide in the UK] set at ½ the included thread
angle. This puts the cutting almost entirely on the tailstock
side of the cutting tool [assuming a RH thread]. This avoids a
very wide chip that tends to result in chatter and having two
chips meeting in the center of the tool causing jams. This also
gives the affect of positive rake because you are moving into the
work toward the headstock. Some very good machinists suggest
setting the compound slide a few degrees less than ½ the included
thread angle to give a burnishing action to the side of the
thread away from the headstock and the added contact is stated to
reduce chatter. I have not found this necessary.

There is an accessory [actually a necessity] called a "thread
indicator" which is a small gear that engages the lead screw.
The gear turns a dial with a number of lines that indicate the
position of the half-nut relative to the lead screw. Pick any
one of the moving lines and snap the half nut in when the fixed
and moving index marks are aligned. I suggest using a magic
marker to highlight which moving line you are using.

Note: This works as long as you are using an inch leadscrew to
cut inch threads or a metric leadscrew to cut metric threads.

I suggest that you buy some of the older lathe books such as
Milne's Machine Shop Methods [c.1944] see
http://www.lindsaybks.com/bks/milne/index.html
The Sheldon lathe manual also from Lindsay is also very good.

If you will send me an email with a valid address, I will send
you a scan in pdf of the section of an atlas craftsman lathe
manual that covers threading.

Hope this helps.