Pre mix it and make sure it's disolved before adding to the aquarium. And you want to go slow or you'll kill off all the bacteria and cycle the tank again. I'd say bring the level up to around 1.008 over the next couple weeks. Leave it there for a while until they start getting bigger, than proceed to raise the salt level.
Thanks, I mix it in a retired betta home let it dissolve and wait a day then add it in, gently raising the SG. It's all good right now and I'm treating them for IP