Welcome to YT, fellow Alaskan
Here's my .02, and it's just an opinion. I'm no expert.
A lot of people say Yorkies and kids don't mix. Some breeders won't even sell to a family with young kids, their reasoning being Yorkies are delicate and kids don't understand that. I know of Yorkies who have broken legs, or worse, when falling from heights or being stepped on. And yes, they are more delicate than a JRT.
That said, I know many families who have kids and Yorkies and get by just fine. The parents teach the kids how to interact with them and how to be gentle.
So that brings us to the daycare. If it were me, I would never allow a Yorkie to interact with a group of daycare kids unless someone was designated to supervise the Yorkie -- and not the person designated to supervise the kids. An emergency with the kids could leave the Yorkie unsupervised, and it's not worth the risk.
If you do have that level of supervision, then I personally would introduce the Yorkie to them right away. Do it one at a time and watch the Yorkie closely to make sure it's not overly agitated. With proper supervision, it could be a great socialization exercise.