Hannah,
Another bit of unsolicited advice....
When you have nursery stock in its original pot and soil, the challenge is balancing the risk of trauma from repotting, versus the risk of root rot or fungus from poor drainage. In my limited experience, I have repotted much more delicate material [rhododendrons and lavender star flowers] at the 'wrong' time of year with no ill effects. The trauma of repotting is from cutting roots, not moving to a new pot. Both of the containers you have seem small relative to the size of the above-ground portion of the trees. If I remember correctly, you are in zone 6, where temperatures can occasionally go below zero. A possible solution might be this: for both plants, get a larger container, at least a three gallon nursery pot or even a five gallon bucket. With the bucket, drill a bunch of hole in the bottom for drainage. Then slip the trees out of their little pots, and gently knock away as much of the nursery soil as you can without injuring the roots. Put the tree in the larger container with a real bonsai aggregate around it. Everyone has their opinion, but personally I use one third akadama, one third Oil Dry [which is bentonite clay], and one third Napa 8822, Dri-Stall [which is diatomaceous earth]. You can then sink those containers into the ground.
This combination will give you good drainage, you'll get the insulating effect of burying them in the ground, and because the roots are not restricted, the trees will be able to grow and thicken when the season of growth is upon them. As a bonus, the bucket handle will make it easier to pull the thing out of the ground when you want to.
This is not based entirely on bonsai experience. I've been raising antique English roses for twenty-two years, and I've used the buried bucket method when I needed to place a rose someplace temporarily, and wanted it to grow out some more.