Social media algorithms that determine how your posts are served to your followers are always changing; the most recent change comes from Instagram.
Instagram now serves your content based on the following rules:
Your relationship with the follower - if they have interacted a lot with your past content, they will be more likely to see your future content.
Interest from the follower - does the follower interact with similar posts and accounts?
The timing of your post - how long ago you posted vs the time the follower is scrolling through their feed.
Try it for yourself: Test out which time works best for you to post content. Try mid-morning, late afternoon and evening and see which post gets the most interaction. This will determine which is the best time for you to post your content and receive maximum engagement.