There’s no average amount of time it takes to do a split because flexibility depends on many factors: elasticity of muscles, tendons and ligaments, temperature of body and air, muscle strength, ability of muscles to contract and relax, neural regulation of muscle tone, time of the day, age(each passing year muscles and joints seem to become stiffer and tighter), and even your psychologic status. And of course any injury or disability will also have an effect on one’s flexibility. So the time it takes you to do a split can vary with all these things and your ambition: if you do proper exercises with an optimal frequency (30-60 min 3-5 times per week) you will reach your goal faster than someone who skip routines.
Plan on anywhere from several weeks to several months. Don’t compare yourself with others, focus on your own progress. The progress can be good in the beginning, and often it slows down at the last portion of your training.
Can Everyone Do Splits?
Even if you think you aren’t flexible or are out of shape, most healthy adults can learn to do splits. Some health conditions, such as acute arthritis or severe varicose can make splits dangerous or even impossible, though. If you have a chronic medical condition or a history of injuries, check in with your doctor before you try to do splits.
You can find stretching tips here.