I dunno about earliest but I have kinned Haruka Kiritani for the longest time Probably about 3-4 years

non-oomf but my first ever kin was Teruki Hanazawa followed up by Tsukasa Tenma !!

I think it was pinkie pie

pinkie pie is the longest one of mine

rodion raskolnikov. probably. can't tell what's a source n an id.

I think uhhhhhh yui hirasawa or hikawa hina were my earliest.

Snufkin (moominvalley)

for me i think it was hutao

lance from voltron. except we firmly don't think it was entirely a kin thing...... the Introjects

Mitsuri and Xie Lian