How much time it takes to experience 4th jhana? Right now sometime if i try to concentrate i can feel the calmness in mind. Before 2 years i used to feel inner joy after doing meditation. If i do meditation everyday for 2 -3 hours, how much time will it take for me to leave the rupa jhana? 

Or simply, is their any time intervals in which meditator experiences all the jhanas one by one?
"Suppose a hen has eight, ten, or twelve eggs: If she doesn't cover them rightly, warm them rightly, or incubate them rightly, then even though this wish may occur to her — 'O that my chicks might break through the egg shells with their spiked claws or beaks and hatch out safely!' — still it is not possible that the chicks will break through the egg shells with their spiked claws or beaks and hatch out safely. Why is that? Because the hen has not covered them rightly, warmed them rightly, or incubated them rightly. In the same way, even though this wish may occur to a monk who dwells without devoting himself to development — 'O that my mind might be released from effluents through lack of clinging!' — still his mind is not released from the effluents through lack of clinging. Why is that? From lack of developing, it should be said. Lack of developing what? The four frames of reference, the four right exertions, the four bases of power, the five faculties, the five strengths, the seven factors for Awakening, the noble eightfold path.

http://www.accesstoinsight.org/tipitaka/sn/sn22/sn22.101.than.html