A couple rock solid rules to follow
1. Do not manhandle the nem out of it’s spot in the tank. If you don’t like where it settles, changing the flow will usually cause the nem to walk somewhere else
2. Keep powerheads protected but at their normal output. If the new decides on a spot then you turn the flow up, this will cause the nem to walk away
3. Definitely temp acclimate! There’s mixed opinions/reviews/experiences with drip acclimation but I’d say either float and drop in or float and add 50% more water to the bag. So if the bag starts with 2 cups of water in it, add 1 cup of tank water; of course, you can eyeball this. Nems are inverts, but they are NOT like shrimp where you gotta drip them for like 30 mins or whatever. Extended drip times can and will stress a nem to death, I made that mistake and now I just float them and drop them in the tank. I’m so confident in this method that I did it with my CSB and he’s very happy now. I’ve got 8 BTA and they were all introduced using the float and drop method so that’s what I recommend but I know that it’s a little intimidating for people used to dripping.
4. The nem is going to do weird stuff. Bubble, be thin, stretch, scrunch up, walk around multiple times per day, etc. As long as the mouth isn’t overly gaping for a long time, it’s not bleaching, and it doesn’t release mensenterial filaments (looks like white worms) then it’s doing okay and you shouldn’t be worried. Nems are weird and you just gotta go with it, don’t let them get your blood pressure up
5. That nem is gonna settle wherever it settles. Make sure you have a plan to move corals/encourage it to move if it picks that ONE spot with a coral you can’t really move. They don’t really sting too much while they walk so make sure you wait like 24 hours before moving stuff away from the nem to make sure it really is settled there.