That's a great question. In my case there are two considerations. One is the "from the mold" part, and the other is the "ultimately" part.
First, when you're laying in the torn-off tail bits to fill out the shape of the bunch in your hand, over-stuff the head somewhat, at least in terms of your perceptions. Tear off the tail, flip it, and lay a good chunk of that into the head. Like twice as much as you're doing now, since now you're ending up mushy. This area tends to be the most likely to end up understuffed; and unlike the foot, you can't just tuck-cut the under-filled part away later. So bias towards overstuffing the head rather than understuffing. Easier to pull something out with tweezers later if you went crazy and made it 6 rings bigger than the body of the stick than it is to try to add something in later.
The second part is that some % of that round head comes from the wrapping and capping stages rather than the bunching. With wrapping and capping you're adding mass to that area, and certain techniques will allow you to lay that new leaf down in a way that tends towards a dome.
Not only do I trim my bunch before sticking it in the mold, but I trim the head again with scissors before I wrap, to make sure it is smooth and round with no extra ridges near the head from the bunching process. It's possible to mess up you're draw little bit if you're too liberal with the scissors at this point, but there's still room to work. You can safely concentrate on the dome more than on the draw; the draw is not likely to get screwed up unless you really go crazy. For one thing, the wrapper will act as sort of a flat-tire patch to the draw.
I hope this helps!