SLOWDOWN actually it has nothing to do with your navigation or with where you're going.
It has to do with astrophysics and gravity. Basically the gravitational pull of planets, stars, asteroid belts, etc cause you to slow down. And all that alert is, is letting you know why you dropped 25-90% speed.
I actually use this to my advantage sometimes when I'm in a hot area with 100+ T of gold in my cargo being chased by undesireables. I run for the planet closest to my station, the planet, not the moon or other, smaller body that may actually be closer to the station. I am for the main planet first at flank speed. I then hit the "slowdown" point and start to get pulled into it, depending on my location and speed in relation to the station, I may stick with it, or then bounce to a moon that's closer to the station, all the while avoiding my adversary.
I just wish it was also accurate in the "sling-shot" around the planets. But then again, who knows what really happens when we go 20+X the speed of light lol
beyond that, I too use the 7-12 second mark to start slowing down onto approach. I usually drop out between 300-500meters. And my approach as a whole is anything but a B-Line to the station unless it's wicked close (under 200ls). Usually I go straight out from the star, perpendicular to the orbits. Then I use some form of reference to gently curve my way into the station. Right now in my Cobra and T-6 I use the top of their canopy as a guide, keeping the station dead-reckoned to the top of the canopy. Then at about 250ls out I start to ease back into a dead-ahead line for the station, usually a bit at 3 o'clock though. I also make sure I'm approaching the system
from whatever it's orbiting. So instead of a straight line, it's a bit of a C or even S curve. It may not be the fastest, but it sure beats getting bored flying in a straight line!
there are some screencaps of my "angle of approach" in this album on my flickr page:
https://www.flickr.com/photos/107989279 ... 4860446536 the big empty blackness at the top is the upper bulkhead of my cobra