Care to share? I've still not found one, then again, I've never really looked.
Scrap what I said. This way is more consistent...
Hover waaaaay above loot lake (center of map) the moment you get off bus. Pull your glider immediately.
When the countdown to first circle reaches 10 seconds left, be about 330m above the lake (put pin in water so you can read distance).
Then when the countdown to seeing the first circle pop up reaches 2 seconds left, pull up the big map and stare at it without blinking. Symbiotes spawn about 2 seconds after the first giant circle appears.
Then just glide there before everyone else.
This way hasn't lost us a symbiote yet.