Need help from a human - I'm moving and need to confirm when the old service will stop and the new service will begin

I'm moving within the same building on May 30.  I want to make sure the internet is working in the new unit immediately on my arrival, or if it will occur later in the day on the 30th, I need to keep my computer set up in the old unit so I can continue working throughout the day.  I tried using the App to keep my service going in the old apartment until May 31 and starting the new service on May 30, but the App defaulted the change to May 31 which does not work.  I'm trying to find out what time of day the change happens if I select May 30 as the stop and start date or if there is a way I can overlap the services by one day (I don't care about paying slightly more due to the overlap).  For example, if I pick May 30 as the date of the move, does the old service stop at 12:01 AM on the 30th and the new service begin at that time, or does it occur at the end of the day? The Xfinity assistant cannot help with this (I've tried).  Thank you.