In the first act, Nora asks her husband if they can't afford to spend a little more on the holiday this year. She says, "It's the first Christmas we haven't had to pinch." While Torvald does not want to spend as much as Nora — she is willing to take out debt in order to have a lavish and extravagant holiday — he does give her some money, saying, "Of course I know all sorts of things are wanted at Christmas." She has already been out buying gifts for their children, so it must be fairly close to the holiday. Further, when her friend, Christina, arrives, Nora mentions the season, calling it "mid-winter," and this description lends itself to a belief that the first act takes place in the week or two just prior to Christmas. Then, at the beginning of Act Two, the Christmas tree stands "stripped, and with the candles burnt out," and Nora says that "to-day [is] Christmas-day." As a result, I suspect that the time between the two acts is likely only one or two weeks.

We are given no precise sense of how much time has passed in this play in between Act One and Act Two, yet I think we can safely infer that roughly a month has passed. In Act One, we are introduced to a Nora who has been buying presents and decorations for Christmas, such as the tree, and who eagerly asks her maid to hide the tree for her so that the children will not see it until it is decorated. In Act Two, Nora begins by giving us a firm time marker:

There's someone coming! No, it's no one. of course - no one'll come today. It's Christmas Day.

So I think we can safely say that the separation between the Acts is roughly a month as this is the normal time between when the majority of people put up their Christmas decorations and celebrate Christmas.