I would email them ahead of time. I wish I had been more proactive about this. I did ask, and was told we had a paperwork hour that I could use in addition to my lunch break. My first day of work, they took away the paperwork hour (for everyone), and I didn't say anything about needing time to pump, partly because my schedule wasn't full and also because I thought they knew my situation. Now, down the road, I realized I could have and should have done a better job advocating for myself because I only pump once in an 11 hour day (9 hours work, 2 hours commute and pumping in the car would no longer work because I need my hands to uh, adjust/manipulate things throughout the session that I didn't have to do before). Now I can't go back and say wait a minute I need this time. Ok, I know this is different from your situation, but my message is advocate for yourself early and often. Plus, if you email, you have it in writing. Good luck!