I was on #TeamDS too and it seemed to me that she claimed Taek pretty much from the first episode. She was looking after him, patting his butt and telling him to grow up and marry her something she didn't do with any of the others, not even when she had a crush on them.
I also think her feelings were pretty clear when she picked the pink mittens even though she had originally really wanted the pink gloves as she told Taek and as JH who was there when she oohed and aahed over them, got for her. Its ironic she didn't pick the gloves JH bought her and he didn't wear the shirt she bought him.