I've been transferring larvae to saltwater as soon as I'm seeing them. Except, it's 3am, I've already moved a *lot* of babies, and there are still a *lot* to be moved and hatched... so those guys may have to wait a tad longer...
And this being from a female that dropped her eggs approximately 2 weeks prior to when they were "due", set up in a brine shrimp hatchery, and hatched less than 12 hours later...
I fed the saltwater tank with powdered algae before I even added any shrimp. Only a tiny amount. (before I even knew I had babies, which, I guess, was 2 days ago from the first female, and only managed to get a handful... as in, could count on one hand... second female, hundreds of babies!)