Instagram Posting Times App. It's as easy as that. It also tells me when my followers are the most active.

Instagram is one of the best channels for businesses to grow online and achieve their marketing goals. With the hootsuite app you can schedule instagram posts to publish later, even if you can’t be at your desk. My next step would be to check his top instagram hashtags.
6am, 10am, and 10pm est tuesday:
This is a good start to test your best time to post. While they ended up with different results, some similarities stood out. It's important to keep a close watch on your instagram insights trends. The best time to post on instagram by day: