I am still a bit new to T5 but we finally downed it tonight and it took me some experimenting to cycle cooldowns properly. It also depends on the party composition. But what I did

Initial pull, pulling adds and twin, FOF, run in, shield lob twin, pop rampart (this bypasses that weird aggro bug at the beginning), then I hit foresight, spam flash, as I throw just ROH's not charged on each enemy. After R and FS wear off I do bulwark and bloodbath, then a sentinel for DS. Then throw in convalescence somewhere in there, by next DS i got rampart again. I use rampart a lot bc its 60 sec CD and its pretty good mitigation.
Its more about when and when not to use CDS in this fight. Some points you wanna save them and some times you are free to pop.

So basically, the initial pull, I pop em all, even HG bc I will have them all when I need them. I dont need many CDs during conflags bc I dodge all DS by running into con flag. If ur group is timing right, you wont get hit by one DS during conflag. Then during snakes, I pop bulwark and then a bloodbath a bit later. Dont use too many CDs here bc u really need them for all 5 snakes.

The most stressful spot imo is all 5 snakes. We had a marauder in our group, so he tanked the big snake while I tanked the 2 littles. Right before the 4 and 5 snakes pop, I provoke the big snake while I already have hate on the 1st 2 little ones. I shield lob big snake while running across to 4th and 5th. On my way, I pop rampart, shield lob left (4th) and flash or lob right (5th) snake. I run back a few steps toward the 3 snakes, then pop sentinel, and then 5 secs later pop convalescence. I try to only do those, our healers could heal thru it, and the little snakes go down quick even with a 2 LB, so they shouldnt do much dmg. Thats only if u dps the first 2 littles ones down before pulling 4th and 5th. So when all little snakes are down, I run to the middle in between the 2 nuerolinks and finish him off there. I dont use any CDs on only big snake, bc u need CDs for dread phase. This is bc of DS and infirmity healing rebuff so u def want a cpl CDs to go into the phase with. I usually have rampart by then, bulwark comes back soon and bloodbath, and conva will be back by like 3rd dreadknight. If you ever dont have CDs or they are too close to tell, tell someone to throw eye for an eye to be safe.

The first cpl days of T5 practice, I did HG on snakes phase, but u dont need it. If you have a few CDs stacked during snakes,along with virus on a cpl snakes and eye for eyes, youll be fine. I actually didnt even use HG during our kill run, but its def good to save if a healer is dead during hatch phase. If a healer is dead and the other is dodging liquid hells, you are screwed lol. Also, HG can be used if you, as main tank, gets targeted by liquid hell. You pop HG, let the 5 LH stack, then move a few steps to the right or left so that when HG is done, you are out of the LH. We got very lucky during our hatch phase that neither MT or OT got targeted by LH, but if it did target me, I was ready with HG. Noone died during our kill run either which really helps immensely lol. Good luck. I know its lengthy but I am fresh out of 6 hours of T5 raiding and this is exactly how I did it tonight. Hopefully you got stoneskin as well. It comes in handy if you can time it right.