You have two challenges in addition to the pruning per se. One is the transition from inside to out and vice versa. The other is care indoors. Pointsettias to do well indoors like as much light as they can get and they love water as long as the potting media is well draining and not kept dripping wet.
I used to to care for many as 400 + Points at a time and have grown a couple indoors for as long as 5 years.
The easiest and best method to thoroughly water them is to hold them over a sink or a large bucket and water til the water flows freely thru them. When it stops flowing place them back in their regular location. Water regularly but allow the media to not be perpetually soaked. Never allow them to have wet feet or sit in standing water.
One question. Did you buy a very large plant and/or variety to begin with? Some are much better candidates than others. One huge variety that I use to purchase a few of each year were close to trees to start with. They came 5 plants per pot and were ~ 5 - 6 + feet tall. Obviously they would be a much easier candidate than a typical 2 - 3 foot plant(s) in a 6 or 8 inch or larger pot.
Were I you, if starting with a pot of multiple plants, I would separate them and have 2 or 3 or more candidates rather than focusing on just one by cutting all the other stems. This would also help in case one bites the dust. That will be easy to do in your zone.
Good luck.
