Here’s a great infographic published by Buffer:

According to Kevan Lee at Buffer, here are the best practices for when to post on social media:

Twitter – 3 times per day, or more: Engagement decreases slightly after the third tweet.

Facebook – 2 times per day, at most: 2x per day is the level before likes & comments begin to drop off dramatically.

LinkedIn – 1 time per day: 20 posts per month (1x per weekday) allows you to reach 60 percent of your audience

Google+ – 3 times per day, at most: The more often you post, the more activity you’ll get. Users have found a positive correlation between frequency and engagement. When posting frequency wanes, some have experienced drops in traffic up to 50%.

Pinterest – 5x per day, or more: The top brands on Pinterest have experienced steady growth – and in some cases rapid or sensational growth! – by adopting a multiple-times-per-day posting strategy.

Instagram – 1.5 times per day, or more: Major brands post an average of 1.5 times per day to Instagram. There’s no drop-off in engagement for posting more, provided you can keep up the rate of posting.

Blog – 2x per week: Companies that increase blogging from 3-5X/month to 6-8X/month almost double their leads.