depends on a plethora of conditions...
1) how old is the plant? from seed, it may take up to 2-3 years for some species while for others like H. hispida and H. ionasii, it can take much longer.
2) do you fertilize/feed? fed plants grow faster
3) do you give it optimal temp conditions? night time drops into the high 40s is favorable.
4) do you give it optimal lighting conditions?
all these things factor into how soon your plant will start producing pitchers. in my opinion, you've got a growing season or two before mature pitchers are produced. even then, during that time, your plant will transition from adult to juvenile leaves before permanently producing adult pitchers.