We have someone calling out when Staghelm gets to around 85%.. which is seconds from him jumping.. remember, the closest person to the orb is the person hit.. so if you run back or off to the side far enough, it won't stack right in front of the orb. Even if it does, it's simply a matter of the closest person to the orb. We would have a healer and a RDPS switch off, which worked well, with a third RDPS standing by for callout.
If one of your healers uses VUHDO, they CAN tell you when your timer is up. I don't know about other addons, but I do know that it shows for all three of our healers. It's best to watch your own timer or at least have DBM yelling at you to get out of the group, however, it worked well for people to pay attention to the raid fully, until their name was called out in vent that it was about time for them to run out. This helped our group a lot and it also helped us healers coordinate better, as we could see when the other healer was going to be somewhat out of range or in motion and unable to help heal the raid for a moment. Mind you, we also run 10m.. I'm not sure how well this strategy would work with 25m.

