Very nice strong seedling. Considering the leaves are happy clappy, the tree should easily survive the ordeal. Not collecting trees in certain times of year mainly refers to the sort of collecting which requires major root-pruning. Seedlings you can move around yearround without any loss if a little care is taken to minimize root damage.
The Manitoba Maple.. Nice article here;
torontogardening.blogspot.com/2009/05/ac...egundo-seedling.html
I would indeed consider giving it a more permanent spont in your garden for 2-5 years. Either letting it whip up to a 3 meter tall thin shoot. That would enhance nebari forming (Place the pot outdoors in a sheltered position now. When it has dropped all the leaves, clip a few cm of the taproot, and plant it on top of a tile, so the roots are forced sideways). The other option is to trim it back to 2 'nodes' above where it was last clipped off (pretty much just above the spot where your grey wrapping is on teh tree) and do this every fall: You will still create trunk and nebari, but your scars will be less obvious.
Nice sapling!