I'm currently trying to raid NH as disc.
I'm finding it much harder to do efficient burst healing and as a result I'm far down on meters.
I'm I doing something wrong or is it simply harder to predict compared to EN?
Is there a guide somewhere for what the best times to ramp up atonement is?
As with everything Disc its down to timing, but it really depends on how big your group is and if you have access to any innervates.
Krosus is easy to predict as Slam happens every 30 seconds so you can time your rupture or atonement blanketing in advance.
Tichondrius also when you get to a certain amount of plagues and seeker swarms.
Gul'dan with the Empowered bonds and EMpowered liquid hellfire
I would say that NH is worse for disc than EN was, but its very boss dependent. In that regard I think that NH as a whole is worse off for Disc than EN is, but it should be doable. Bigger groups is better than smaller groups, but that has always been the case.
Holy is pretty much throughput king in Nighthold, across all healers. Long fights make Enlightenment better, the damage patterns are very favorable to the spec, and Prayer of Healing during Divinity is ridiculously strong.
How2Priest has amazing guides for all the priest specs, if you haven't read them yet. They also have an active discord channel.
Disc is problematic in NH. Many of the fights are long, mana dependent, and require many bursty healing CDs. As a result, Disc finds it hard to perform compared to the other healing specs.
Incoming damage isn't harder to predict, but it is more frequent, and many fights have mechanics that deal massive damage raid-wide. It's not just you, many disc priests are struggling to keep up in Nighthold.
If you MUST stick with Disc, I would get an add-on that shows boss timers, and move it somewhere that it can be easily seen. This will help significantly for knowing when a damage spike is coming.
From my experience of 7 / 10 heroic the only bosses that I find are disc favourable are Chronomatic Anomaly and Tichondrius and Spellblade the rest of the fights tend to have an abundance of aoe or spot damage on frequent timers so much so that I personally try to cover too much and gimp my self mana wise usually around the last phases of those fights which needless to say kills my overall performance. On fights like Krosus Disc can do well due to the consistent timers but you can be crippled if the other healers in your group choose to overlap healing on your burst windows or if you simply try to heal too much and go oom to early.
I find as Disc that in general if your struggling its one of a few factors that can usually be easily resolved, Ilvl for obvious reasons, Timing and mana conservation, and lastly good healer communication i.e if you plan to do mass atonement healing make the other healers aware so they don't also blanket the raid, Disc in this respect is the easiest to troll healing class.
Skorpyron keep a healthy amount of atonements and penance when he does the bursty shit
Trilliax maniac phase (mana rupture)
Spellblade fire animate or arcane detonate
Krosus orbs, slams obviously
Tich is a great fight for disc, unlimited mana, constant raid-wide ticking, just keep a ton of atones out and play normally
Augur ice nova and the fear thing from add during last phase
Botanist shadow AoE thing, orbs, multi-dotting with PtW makes this a great disc fight
Elisande red add cuz they do raid wide damage. Innervates have low CD here bc of the red buff. Use sfiend/rapture often to take advantage of reduced CD
Guldan helfires and black harvest
Disc is great in NH idk what everyone else is talking about
I've found NH much easier on my Disc than EN was - this week I was top heals on 4 out of the 6 heroic bosses we downed (with no innervate, and my co-healers are no slackers). I destroy on fights like Tichondrius and Spellblade because I can maintain huge raid healing through a much longer window than just the 8 seconds of a Tranq or similar. Krosus I can also cover more Slams than my other healers since my burst is on-demand with no cooldown. The key for me was finding what abilities in each fight are doing the most damage, and planning my atonement count around those - Mayna listed most of my key ones above.
That being said, I occasionally go Holy when we're learning a fight (since I don't know the damage patterns yet), then switch to Disc once I've got a handle on what I need to cover.