You will get a lot of different answers on this one. I have seen this topic before.

From what I have read and know, they will go when they have too. Make sure your temps and humidity are ideal and watch for signs of stress. If all is well, then nature will run its course.

Also it would not hurt to keep a calender or journal of some sort on feeding shedding defecating etc... After a while, you may see a pattern develop and if it changes, you will know something is possibly wrong.