Recipes are normally just that, a list of ingredients and to some degree directions on how to mix them. Unfortunately a consistency in wine recipes does not exist. Folks don't always discuss how long to age, how often to rack and especially not how often or even IF you should add certain things like K-Meta.
Basically I think a lot of folks assume that the readers will know what the 'standard' process is for wine making once the ingredients are listed along with any 'special' preparation actions.
Safest thing to do is to find a pretty standard approach and use it until you find a better way. So for a quick and dirty list of what is "Normal" let me give this a quick shot.
1) K-Meta is normally used before you add your yeast to kill off bacteria and 'bad' yeasts. Some kits or pre-prepared juices will tell you you don't need to do this. With a kit - follow their guidance. With juices keep in mind anything other than the juices you add could introduce bacteria.
2) You wait 24 hours and then you add your yeast.
3) K-Meta (or Campden tablets) are normally only added after the fermentation is completed. (At and SG of .990) If you add before then you wine will still have some residual sweetness. That may be part of a kit or recipes design.
4) After fermentation is completed the most common routine is to add k-meta/campden tabs at every other racking to keep a enough SO2 in the wine to preserve it. And then just before you bottle it (A week before normally is a good game plan)
5) Potassium Sorbate is used if there is any residual sugar in the wine OR if you back-sweeten it with sugar or an F-pack that contains fermentable sugar. It can induce a flavor that some people detect but either you add it to a sweetened wine or risk bottles exploding or blowing out corks. It, Sorbate, is not needed if there is no residual sugar. The best plan is not to add Sorbate until you add your last k-meta dose before bottling. (Again about a week ahead of bottling.)
You are correct that opinion does weigh into a lot of what people do. Few of us home-wine makers have enough chemistry equipment to get exact measurements and be 100% on the numbers for things like the ABV and SO2 content in the wine as it ages and before bottling. So a lot of what folks do comes from their experiences and trusted recommendations from friends and folks on forums like this.
Hope the helps! Hang in there in a year from now you will be enjoying some great wine.