So, how's the other clown today?
The reason we don't add LFS water to our tanks is that the LFS water can contain bacterial contaminants (parasites, disease-causing organisms, all sorts of nasty stuff) that would harm the inhabitants of our tanks. That's why we use quarantine tanks -- to ensure the health of our newest pets before introducing them into our larger community tanks.
Like you, I added my first three fish to my tank directly without visit to a quarantine tank -- two false percs and a LMB. After three and a half weeks, one of the clowns developed marine velvet and died. I was lucky that the other two fish did not get it. After that, a 6 week stay in the quarantine tank became mandatory for anything live that goes into my tank.
Bare-bones acclimation procedure is to float the bag in your tank for 20 minutes to allow the temperature of the water in the bag to match the temperature of the water in the tank. Then open the bag at the top and add about a quarter cup of tank water, making sure that the bag water does not get into the tank. Let the bag float for about 15 minutes and then add another dose of tank water. Repeat several more times. If the bag gets too full of water, use a different cup to scoop water out of the bag and discard that water. Don't use the same scoop to take water out of the bag as you do to take water out of the tank to avoid cross contamination. After a hour or so, net the fish and put it in the tank.
Welcome to the world of marine tanks! And
[welcome]