You think you’re on time, but when you get to shul, they have already started and you missed borchu. Setting a clock or watch ahead solves that.
Know what else solves that? Stop playing “Jewish Time” and simply train yourself to be on-time. Believe it or not, much of the rest of the world manages to get things started on-time, like weddings, family celebrations, graduations, meetings, etc. Gee, maybe I should post this in the Pet Peeves thread!