Mittelstadt's next game in Buffalo is expected to be his NHL debut, when the Sabres host the Detroit Red Wings at KeyBank Center on Thursday (7 p.m. ET; MSG-B, FS-D+, NHL.TV).
"It's definitely been a whirlwind, I'm not going to lie," Mittelstadt said Tuesday. "I think making my decision and then traveling out here so fast, getting on the ice and trying to do the little things, trying to get myself ready for Thursday, I think it's been a bit of a whirlwind.
"But at the same time, I feel like I've kind of been through it before although obviously a little different. The stage is a little different when I went from [ juniors with USA Hockey's National Team Development Program] to high school [in Eden Prairie, Minnesota] to right back to juniors and then the draft combine. All that stuff I think honestly kind of prepared me for it, and obviously this is on a whole new level getting to come here and play in the NHL, but it's definitely been a whirlwind."
Mittelstadt said his decision to sign with the Sabres rather than staying in college was one he had to think about carefully.
"I think I wanted to make sure that the decision I came to, I was both feet in," he said, "and I think I took a few days, almost a week, to weigh it out and see what I wanted to do. It came up over and over again that both my feet were in to go pro and play in the NHL."