Essential to making this technique work…
In illustrator create an additional “reveal path” for each object you want animated separately: One continuous line that covers the object... drawn in the order I want it revealed. The reveal path serves two purposes...
––A layer mask that drives the stroke effect to reveal art layer
––the hand layer’s motion path
import your saved artwork into AE
NEVER SCALE THE ART LAYERS IN AFTER EFFECTS (see step “Align the Hand”)
switch back to illustrator, select and copy the reveal path of that object
switch to AE, paste copied reveal path on art layer to create a layer mask
add effect Generate > Stroke, set path options to "All masks" and check "Stroke Sequentially"
under effect options set Paint Style to "Reveal Original Image"
add a picture of a hand holding a marker to your main comp and then precomp it
set anchor point to where the marker tip is
click the position stopwatch and paste previously copied reveal path to create a motion path
The art layer MUST BE 100% scale, otherwise the motion path won't match the art layer's mask. After creating the motion path in the hand precomp, you'll need to reposition the group of keyframes so it aligns with the art layer's mask. Select the keyframes you just pasted, place your playhead on the first or last keyframe, drag the hand layer into place (3:28). This should reposition the group of keyframes instead of just one.