just bring it up to temp, float the fish in the bag for 30 mins and add a little tank water to the bag
leave it 24 hours then test for ammonia / nitrite
if they read 0, cool beans, test again in 24 hours
if you see any ammonia / nitrite reading, make sure it doesnt go above 0.25ppm by diluting it with water changes
i usually test for a further week and if its all good after that, just test weekly for a month, after that, everything should be fine. I've probably not tested the water in my tank for well over 6 months now.