The physical act of keeping track of what happens when is not as difficult as you might think. Simply print out a calendar that shows the dates of a given month that match the days you need. For example, let’s say you need two people to meet on February 6th and it must be on Saturday because the meeting occurs at the Saturday Farmer’s market. I would print out the February 2016 calendar and use that as my reference, populating the events on the page. Then you have a visual one-page reference tool for the entire plot.
The real challenge goes back to the rigor of the outlining process. The first (and most critical) step is to understand when the key events of the plot occur relative to each other. From there, simply fill in the days on your paper calendar. And use a pencil.