Agee 100%The VFL started in 1897, not before, not after - so 1897 is the only factually correct answer for when to count Premierships in this league.
The VFL were never called the VFA - the VFA was an entirely separate organisation from which a bunch of clubs broke away from after the end of the 1896 season to form the VFL as a brand new league (which later named themselves the AFL in 1990, but have otherwise continued, adding new clubs over the years since 1925 when 3 more defected from the rival VFA).
Thus, Premierships for the rival VFA organisation can’t possibly be included as VFL/AFL premierships..
But I would not put it past it that AFL might re-write their history if they find it fit to do so.