Post Insights are collected and reported in real-time (or near-real time), and are not aggregated by day, week, or 28 day period. In other words, you won't be able to get historic data but you could run a scheduled job to capture all of your posts and the metrics you're after each day.
https://developers.facebook.com/docs/graph-api/reference/v2.2/insights
In my experience, running the job in shorter intervals (10 minutes, 1 hour, etc) and seeing how post metrics evolve by time of day and day of week is a valuable exercise.
You can make 600 calls every 600 seconds - might as well make the most of them.