There is a brush in illistrator you could use to make the ink drops. Make them different layers for each drop.
Try animating the scale of the drops in AE, maybe set keyframe to ease in so they grow fast then ‘bleed’ out slowly at the end. Also mess with blending modes so it looks more like its soaking into paper.
Someone else might know a better way of doing this, I guess it depends on the level of detail you need and how fast it will all happen.
Josh.