California Prop 19 and primary residency length of time

[Miriam Velazquez]

Hello everyone. My husband's mom wants to transfer her house in California to him. With Prop 19, this will trigger a re-evaluation of the property unless my husband makes the property his primary residence. We are willing to move in, but we are not sure how long we are expected to live in the property.  Does anyone know how long we need to have this property as our primary residence?