Hi Kaito,
It's great that you are looking ahead several years to your future career steps. It sounds like your academic success as well as involvement and extracurriculars will strengthen your application to a top B-school, and even your travel time could be a plus if you are able to explain what you gained from it (international exposure, cultural experiences, etc).
Beyond that, at this point the rest is still up in the air. The GMAT exam is a very important factor in your application, as it is meant to be a predictor of your success within the program, and can help you decide what tier of schools to aim for (as you compare your score to the average at those programs). I would recommend considering taking the GMAT sooner rather than later, or when you are at a point where you can spend 2-3 months preparing for it (part time) and making sure you hit that high score you are aiming for. The scores are valid for 5 years so it's great to get that done well in advance of the application season.
Focus on staying involved in the community and in activities you are interested in, and within your work experience, taking on leadership roles where possible, working on team projects, people management skills, project management skills, etc. Since you are already focused on an MBA down the road, you may want to start (when you start your next role) jotting down little examples of times that you demonstrated the above mentioned skills, in a file somewhere that you can save until it's time to apply and write those application essays.
You will usually apply 9-12 months prior to when you plan to start the program. For a standard fall start, you'll want to start preparing for your essays/applications over the summer (14-18 months before you'd begin) or thereabouts.
Keep following boards like these for tips and good luck to you!
Hope you are enjoying your travels!