Hi Portia,
It probably depends on the person. I started Bifido 4 weeks ago, 3/4 pill a day. I had a great week, then an awful week. Foggy head, headaches, tiredness, lack of focus, urethral pain and rawness in that area, so Matia reduced the dose to 1/4 a day. After 4 weeks, she wants to try raising it up to 1/2 a pill a day. She said the bacterias in this probiotics are strong, and cause discomfort at first. The idea is to introduce it to body slowly when your body is able to accept it and not to force it on your body. So it depends how you react to it.

So hard to answer b/c everyone reacts so differently... some adjust in days, others weeks, others months.  If it's really too much for you, she'll often pull you down or off it for a while. But it can make an appearance later once you're further along, and you'll be surprised with this -as with the other herbs/supplements- how something you couldn't tolerate before or gave you certain die-off before can have a very different experience the next time around. 
I remember when I first started on Bif I had die-off for sure incl. some intense gastro issues but I was tolerating it and helping bladder, so she kept increasing the dose. I think I was on 4 pills/dose! with maybe a Mega too?  My gastro stuff got so strong that my bladder got worse -- not from the Bif itself but from all the pushing on the toilet clearly b/c of the Bif, so we had to back off.  But I've been on/off it several times since.