Distrubtion server replication times

When does the patches downloaded to the central server get replicated to distribution servers? Let's say i have an APD at 4:00pm and thee deployment window is 7:00pm to 10:00am when would the patches be replicated to the distribution server? We want to minimize the bandwidth between where our central server and the distribution servers are during the day and would like it to sync all patches to the distribution servers after 6:00pm. This is due to a backup that we will have going on throughout the day to another remote server from the same location as the central server and want to keep that pipe open with as little network congestion as possible. Any information on how to change the sync times or how it downloads patches and how it effect traffic would be great.