December/January was the guesstimation for Ryan Whitney's return, so to say he's on pace for such shouldn't come as much of a shock. At least, however, there haven't been any setbacks to alter the full-time return, so we can focus on that.
Whitney is still testing out his foot lightly in practice. If I had to guess the training staff is hawk-eyeing the entire time to make sure he doesn't overdo it, take a puck off the skate or show any signs of dragging/limping. Given last year's too-early-return of Sid after his high ankle sprain, the training staff may have learned a thing or two about players' stubbornness.
"It's kind of week-to-week. Once you get a day off, usually it feels better the next day. Hopefully, at the end of the road trip this week, I'll be doing everything in practice."
Improvement, in any sense of the word, is exactly what we're looking for here. Even the announcers during the Devils game suggested Whitney is expected back around the third week of December. What fact/speculation they are basing this off of, I don't know. But I'm going to shoot out my own spec as well and say we can expect him back on the ice no sooner than January. I'm also going to say that is up for change considering the Penguins' record throughout December. If the PP continues to struggle, or if the team enter a funk, then I'd expect they may try and rush Whit's return.