I'm going to recommend that you start by getting 24-50 hours of shadowing (e.g. three to six workdays of 8 hours each) physicians including at least one physician in primary care (general internal medicine, general office-based pediatrics, or family medicine).
After you've seen what the workday entails from the physician's side of the exam table (it is different from what you see from the patient's perspective), then consider a formal postbacc program.
If your goal is to "help people", show me that you are willing to do that now with whatever skills you have as a volunteer. Ideally, you help people face-to-face and the people are different from yourself (much older, much younger, much poorer). The work need not be clinical, you can help with tutoring, mentoring, adult literacy, food and shelter services, etc. Aim for 6-8 hours/month, month after month. You'll get to know more about people and have the opportunity to build teamwork and leadership skills with other volunteers.
At some point, you'll need some clinical activity beyond shadowing. You are going to be spending several years in a hospital environment, even if you ultimately end up in an office-based practice, so you might as well get a feel for it and understand the rules, the pecking order, and all that. Hospitals operate 24/7 so you should be able to fit volunteering or a paid job into your schedule at some point before or during your post-bac. You'll want to have at least 150 hours of clinical activity before you apply and, of course, can accumulate more during your application year.
After you take all the pre-req courses, or shortly before you complete the last of them, you'll need to prepare for and take the MCAT. This is a 6 hour exam that generally requires about 300 hours of preparation. (someone can correct me if I'm wrong, most of my info comes from self-reports of applicants to my school who did very well on the exam). Factor that in to your timeline and don't rush things by taking the exam before you are ready. Like chewing gum, it will stick to your shoe and follow you around for a long time.
BTW, the application cycle opens in May and the common application (AMCAS) is submitted by July 1 (ideally) with the hope of starting medical school the following summer/fall. There is a secondary application to just about every school. Interviews are required for admission and tend to take place between August and March (this used to require overnight trips for almost every interview but most schools are doing virtual interviews now and unlikely, I think, to go back to the way things were prior to 2020). Offers of admission go out between October and April with some waitlist movement through the late spring. It is a long and costly journey so it is best to be prepared with eyes wide open.