Earning a bachelor's degree is expensive and time-consuming. Many undergraduate students pursue Advanced Placement (AP) courses in high school or transfer coursework from degree-granting institutions. However, the effect of those transfer credits on the time that it takes students to graduate (time-to-degree) is currently not well understood. We have investigated how incoming transfer credit impacts students' time-to-degree by defining three independent groups of transfer students: (1) those entering with College-level transfer credit, (2) those with only AP-level transfer credit, and (3) those without any transfer credit. The time-to-degree has been shown to be statistically different for each of these groups, with students who enter with college-level transfer credit graduating with the fewest semesters. We have explored differences in time-to-degree for students majoring in Physics and specifically for those who are traditionally underrepresented in the field. Cohen's d results suggest large negative effects on the time-to-degree for Physics students without any transfer credit, especially for female students and underrepresented ethnic or racial minority students. These results provide implications toward how universities support graduation in four years, as well as other impacts toward student financial aid such as four-year scholarships. This work was supported by Michigan State University's College of Natural Science and the National Science Foundation (DUE-1725520).