Depends on the hybrid and what I want from that particular plant.

If it's a Sativa dominant strain and I want to maximize the sativa effects (head high/euphoria/trippy/etc) then I harvest like I would a sativa (while the trichs are milky/before they turn amber), if I want to highlight the Indica heritage (couch lock/mellow/pain relief/etc) then I'd wait till the trichs turn amber.  

If it's an Indica dominant strain and I want to go all in on the Indica heritage then I'd wait to the trichs turn amber, but if I wanted to highlight the Sativa side I'd harvest before the trichs turn amber.

Picking harvest times isn't going to make a Sativa strain an Indica one but it can tweak the effects quite a bit. Harvest based on your own preferences. :)