It's best to have a plan in mind before you get too far. Scrog will add to veg time, but is going to increase yield of done properly. If that's what you want to do, I would start reading up on it now.
If your gonna scrog them I'd say do it. Let them fill in the screen for a few more weeks and keep them trained to grow under it. Then flip the lights when the screen is 80% full.
The plants will keep stretching for a couple weeks and you can keep training them until the flowers start to show.
In a scrog you want a sturdy secure screen or net so that it holds the canopy in place you can actually train the plants growth evenly.