The best times to share your content on each platform may depends on various and several factors like the nature of the business, the requirements and needs of your audience and many other things.
The market is full of many analytical and marketing automation tools that may help you to do exactly that though best analysis of your audience, their "times" active in social media. Such tools include : HootSuite’s, SocialBro, Topsy, Timing+ and SocialFlow.
Best times: Weekdays 6:00-8:00am and 2:00-5:00pm
Worst times: Weekends 10:00pm-4:00am
Best times: Weekends 1:00-3:00 pm
Worst times: 8:00pm-8:00am
Best times: 9:00-11:00am
Worst times: 6:00pm-7:00am
Best times: 7:00-8:30am, 5:00-6:00pm
Worst times: Monday and Friday, 9:00am-5:00pm
Best times: Saturday, 2:00-4:00am and 8:00-11:00pm
Worst times: 1:00-7:00am and 5:00-7:00pm
Best times: Monday, Friday, and Saturday at 11:00am
Worst times: 11:00pm-8:00am