I would watch her *very* closely for the next 30 days or so, though. As you said, this is the "crucial" time. Poecs have been known to munch their eggsacs, so if you're especially concerned, you could go ahead and take it away from her early (I've taken eggsacs away from spiders as soon as 3 or 4 days after laying the sac, and they've turned out fine with some extra monitoring).
Good luck, and post some pictures
Also, out of curiosity, how long after breeding did she lay the sac??
We're going to leave it with her for 30 days. She is in an out-of-the-way spot and Tamara and I are willing to risk it. I don't know when she was mated, as that is in Tamara's record book and I don't know where it is. We really need to clean out our office. If I had to make a guess I'd say 5 months or so.