well i can't answer your "timing" question but a hint: if the bear runs you still can aim / shoot on it's avatar - a good trick is to "Call down Thunder" on the bears avatar when it ran to make it come back
on the other hand i'm on slow 3G connection (with about 25 kb/s up/down with HnH) and i don't have such a huge delay - it's more a matter of training to get the right moment to shoot - also there a 2 methods: fast shooting (aim meter is in yellow, bear twitches =shoot ) or letting the bar fill completly while the bear twitches different times, shoot when full and bear has just twitched - as long there isn't real big lag it always works