when I do look back, I tend to end up with the fly wayyyyyyyy right on the forward cast.
Stand with your feet parallel to a straight line (sidewalk edge, out of bounds line on a ball field if one is close by) and cast along that line (across the front of your body) with the rod held horizontal (parallel to the ground)
. This will make it easy to see what you are doing without having your shoulders or neck screw up your tracking.
If there is a real line there, it will keep your line straight from backcast to forward cast (180 degrees). Breaking the 180 degree rule results in either tails or wide loops.
What you are talking about is called "slide loading" and something that most people who double haul and fish a lot usually wind up doing instinctively with time. But I don't think it is a good idea to get newcomers, who have yet to develop a backcast, thinking about starting the forward cast earlier. Most start it way too early as it is. I think the first step is learning to get the backcast to straighten out fully. Once they accomplish that, they will be able to feel the rod loading on the backcast. The next step is to anticipate that loading and advance the timing on the forward cast.
But I think you are getting too advanced for a newcomer.