It's such an open question, it depends on many things.
Some people may have a natural aptitude for martial arts, if you are good at dancing then that is the case.
Then there's the numerous types of martial arts out there with differing philosophies and styles, some of which may be suited to your personal attributes and likes, therefore you'll take to a particular style quicker.
The name kung fu is just an umbrella name for Chinese martial arts, there are hundreds of Chinese styles that differ, e.g wing chun is about hitting and blocking at the same time & straight lines, tai chi is more internal and about circular movements, also about cultivating chi energy.
There's no short cuts other than intense training, how much time can you dedicate to it? Once a week for an hour and it's probably going to be 10 years, although there are many places that do intense shaolin training in China, here you live like a monk for several months and do it everyday for hours on end.
Why do you want to fight like Jackie anyway? He's old now.