Everyone is guilty of procrastination. When it comes to choosing between spending time with your friends and doing homework, the choice is often easy. Sure, you feel guilty, but it doesn't stop you from doing it. Unfortunately, this usually has consequences for your grades.
So, how do you stop it? We all would like to be able to declare "That's it! No more! I will never procrastinate again!"... and have it actually work. Say it as often as you want, I don't know anyone who could reform such a long-standing bad habit overnight. Instead, I found a different, much more effective strategy: productive procrastination. This may seem like an oxymoron, but hear me out:
Everyone has things they enjoy doing - things that we are motivated to do. In most cases, study isn't one of them. However, to help me overcome this, I found ways of incorporating study into the things I enjoy. The main one I used was drawing - when I was bored, I would sit around drawing pictures of things related to school. It was enjoyable, and helped me to remember important diagrams for subjects like Biology. At the time, it didn't feel like study because I would draw pictures that had nothing to do with my homework/assignments/exams at the time. Nevertheless, it still helped me in the long run by getting those imagesinto my long term memory. I also found it easier to understand more difficult concepts in Chemistry by drawing diagrams.
It still counted as procrastination because I would spend ages drawing something irrelevant to my class, but it became helpful later on. Also, by working on something relevant to school, it can lead you on a productive train of thought about the topic - maybe bring questions to mind that will highlight the areas you need to work on. Remember that in IB, the final marks - not the term marks - are the ones that count, so an activity that isn't pertinent to your upcoming assessment could still help you for the big, important stuff.
Find an activity that you enjoy that can help you. Use your time wisely - if you play sport and do Biology, think about what your cells are doing to allow your muscles to move. If you're driving, think about the Maths behind acceleration and speed, etc. IB is relevant to your daily life, you just need to look :)