HUGS. My kids periodically go through stages of being really hyper and unrully at bedtime.
I don't think you can plan in advance. I mean you can, but if you try to have a new routine established in the next 2 months, it will be very stressful for everyone if you try to prep the kids in advance. The idea that they have to be quiet when the baby arrives might be scary to them, they miss their daddy and feel your stress, and feel that huge changes are coming. When they see their little sibling, it will be easier for them to understand and relate. Besides, it is very likely that the little one won't be as sensitive about noise as you think. I did ask my kids to be quietER, but I never got too panicky about the noise. I believe things will fall into places when the baby arrives, and a new routine will just emerge naturally.
At one point I had a craft table set up for the older kids, when I was putting the newborn to bed, and later we all joined her. Or I had her in a sling as I read to them at bedtime. Sometimes I let my older two watch cartoons when I was putting DD2 to bed. It was NEVER as difficult or stressful as I thought it would be, and since DH travelled a lot, I was quite often by myself with the kids.
The only thing that really scared me, was to have all 3 of them throwing up at night, when DH was away, but this never happened.
I think co-sleeping is wonderful, we all love it, but it has its challenges. For me, going with the flow was the best solution. The bad stages always resolved themselves, and in retrospect, were quite short.
ETA: I just read some of the discussion above. FWIW, our kids go to bed at the same time as us, and this is what we enjoy as co-sleepers. When I need more time to myself, I get up earlier than them.