Let's backtrack just a bit.
There are different uses for kmeta. Initially, kmeta is used as a must additive to set back wild yeast and spoilage organisms for the purpose of giving your chosen yeast the opportunity to dominate the ferment and to prevent spoilage while the must is being turned into wine.
Post-ferment kmeta is used to preserve and to protect against oxidation. Post ferment requirements are different than must prep requirements.
Pre-ferment most use the standard addition of 1/4tsp unless the fruit/grapes have an abnormal degree of rot/mold/etc. Personally, I don't used less than sound fruit, but I guess sometimes there isn't a choice. Unless the condition of the fruit is suspect, I would stick 1/4tsp/5g. Regardless of the amount used pre-ferment, you want to keep some stuff in mind. First, by the end of the ferment, there will likely be zero free so2 remaining. However, there will be bound so2 which -could- inhibit MLF. If you're planning MLF, plan so2 additions accordingly ....
Second, if you do an extra large so2 must addition, make sure you give the appropriate time prior to pitching yeast. While commercial yeasts are more/less so2 tolerant in general, high doses can lead to stressed yeast, which frequently manifests itself as h2s.
Really, I would keep it simple. Use sound fruit, normal so2 additions, good sanitary practices and sound methodology. Don't fret the decimal points and enjoy your winemaking experience. Wait until later to plunge into the deep end of the nit pool - the tickets are expensive and demanding on one's time.