Try posting between 5-7am local time on Instagram. For many people, Instagram is the first app they open before they even get out of bed in the morning. Target those users by posting between 5-7am.
Want to know an easy way to grow your social media following & engagement organically? Dedicate 15min a day to engage on others' posts: posts by people you follow and posts that use the hashtags that are relevant to your own audience. LIKE their posts. Leave a thoughtful comment on their posts. Send them a thoughtful DM. Engage with their Instagram story. You can even do this by setting a timer for 15min, so you can invest your focused time on it without getting distracted.