You have to stretch every day. Every. Single. Day. Don't let yourself go to bed at night without stretching, you can do a full body stretch in about 15 minutes, hold each position for 30 seconds when you start. Don't stretch until you are in agony. If you miss a day don't get discouraged - try again tomorrow. Don't ask people how long it will take to start getting more flexible, only you can find that out by actually stretching.