Every breed and genetic line is a little different. I raise Holland Lops and they usually go through their first molt around 8-12 weeks of age. Then again around 6 months, and another around a year old. After that, they usually molt about once, maybe twice, per year.
Not every molt is a heavy one. Sometimes you wouldn't really know they're changing coats except that they seem a little rough in condition. Other times, they blow the whole coat to the point where they have molt lines in their fur or the fur seems to be just falling out when you pet them.
