when I first got my syrian Daisy, I didn't know so much about hamsters and had a small container of sand for her which she barely used. a few weeks later I learnt some more about hamsters and gave her a large shoebox for a sandbox just for fun to see what would happen and she literally moved into it! she became obsessed! she's a real hoarder and would empty out her food bowl each day and stash it in the shoebox. she moved her chew toys, and a bunch of her bedding in there also! eventually I realized it was becoming too trashed up and ordered her a proper niteangel sandbox which is actually coming tomorrow and I'm super excited about it
so like Luna said, my advice is to try a large one and see what happens. good luck with your new hamster!!!