I like healers they do a great job but im torn on this as a tank i always respec before i enter the instance i mean you have like 30seconds + to do it when the que pops. What it comes down to is who's time is more important yours or the groups?
Its really 4 v 1 on this issue. Its like saying its your $15 a month but our combined $60. Same thing with time its your 10 seconds to respec and 10 seconds to drink but its our combined 80 seconds of sitting around waiting on you. Would the group like it if i showed up as a dps then told them to wait while i respeced to tank changed gear, seals, and drank to full mana.... the answer is no.
Simply put if you are considerate and show respect to your fellow party members you swap specs before entering the instance. Now i always check healer mana and will wait if needed but still as a common courtesy to the group swap before you enter.
On the issue of healing ques being a couple of minutes often when the que window pops it will repop even if a dps misses the que so by respecing you're not hurting anyone.
So if I understand you correctly,
-swapping spec and drinking while "enter dungeon" button is up, perfectly fine
-swapping spec and drinking once in the instance, not okay
despite the fact that the rest of the group would still have to wait the same amount of time either way?
respeced to tank changed gear, seals, and drank to full mana
Spec swap is five seconds. Gear, most of us that swap frequently use equipment sets, and even if you don't it's not exactly a labor-intensive process to swap. Seal is one global, again not a laborious thing. And as for "drinking to full mana" as Prot, that takes MAYBE five seconds with a level90 water or Pearl Milk Tea. And by the way, tanks do this ALL THE TIME in randoms.