Applying for Medical School in a year, trying to sort out my work/volunteer priorities.?

Quick outline of my situation:

-1/3 of the way through my post-bacc program, will finish in a year (May 2017) and will take the MCAT/apply that spring for August 2018 matriculation

-Have about 30 hrs shadowing so far, with more planned in the future (max 75 hrs, ideally)

-3 mos. volunteer experience at a clinic last year (2015)

-Working approx. 25 hrs/wk as radiology patient transport

-Bartending 1-2 nights a week to help pay the bills

Between studying enough to keep a 3.8-4.0 GPA and working enough to keep a roof over my head, finding time to volunteer is proving difficult. I'll have year+3 mos. to work and volunteer after my post-bacc is finished and before (hopeful) matriculation, but is that too late to add volunteer hours to my resume? I know you can update your AMCAS app as your resume grows, but I'm wondering if I need to try to fit in regular volunteer hours now and put working on the back burner?