Artificial swarm otherwise known as shook
A slip of the key, maybe. SS, it should have been. But you likely know the difference is much more than desribing them as the 'same thing'.
Any 'set dates' for SS are immaterial. Timings will depend on the season. When they are ready is the important thing. I think earlier the better, given they are fed a little or a lot as the situation demands. It would appear you are only changing one colony in the spring, so no real worries and you might want to transfer capped brood to other colonies, remembering that 80% of the varroa will be in there.
That may be very little (if treated effectively), but the extra brood (don't overdo it for any one colony) can be a help to the other colonies. Just wait until the time is right before making any decisions, apart from having the kit ready and available!
Regards, RAB