When I recrystallize I just set the solvent at room temperature and cover it up with cheesecloth and let it sit like that for about a week or however long it takes for the solvent to evaporate. I am left with large crystal structures (with mimosa anyway). No need for a fridge or freezer that way.
Another thing people do is switch up the crystallization container from the fridge, to the freezer, to the fridge, to the freezer etc. This lets the crystals melt and then rebuild themselves.
Use a the smallest amount of solvent you need to dissolve the DMT before precipitating. Also, if you have a crystal already you can throw that in the solvent (when it cools a bit) to start crystallization on.
That first crystal you posted is nice though, nothing wrong with that baby! I'd say you are having decent results already