Certified GKH Gardening Expert
In the US, Christmas trees can be fir trees, pine trees and many others. I know that they are very slow to grow from seed, so a bit of patience is in order for these little seedlings. I am concerned, though, that the pots are too large for the seedlings. This can cause overwatering issues. Try moving them to smaller containers and when they are six inches tall they can be transplanted outdoors.
Here's an article that may be helpful: