Do you have people clearing p1 of t6 in one sitting? Do you have a few others doing 1M+ in t6? Do you have 50 people, each with a squad that can go in? Of those 50 do you have 30 with more than one squad?
If you answered yes to all of those, you'll walk right through it.
If you think you'll be cutting it close, set up a plan. Put your best TM teams (if you need more than 3-4, you're in trouble) on p1. Assign p2/3 duties, split you next best 10-15 members that aren't on pigs into two groups. One group uses A squad on p2 and B squad on p3. Other group uses B squad on p2, A squad on p3. Everybody else waits until p4 and then you just throw bodies at it. If you do indeed have 50 members and you make it to p4 following the above, you'll clear it easily. Don't allow people to waste damage by having two people finish off a phase together. If you get to 5% left on p4 and you don't have anything left, this will be why you didn't complete it.
Now that is a lot of trouble to coordinate, but the other thing going through that is that it sets your guild up for guidelines in the raids to come. Eventually, you'll clear it so easily you'll have to start setting rules so that everybody gets on the board. You'll have to start limiting people to one turn in the first 24 hours, or saying you can make a 0 damage attempt for the first 24 hours to get on the board, or something else that limits how fast you kill it. Start off with a plan and it'll be easier to get your guild on board with the eventual plan you'll have to have so that everybody reaps the rewards.