It depends on how much followers you have or What type of story you are tweeting? If you have good followers than you will get good hits on your site. I personally tell you, when I tweet on my post than i get 50 instant hits on my site. So, what type of followers you have, it matters...
I'm from England, but most of my followers are from the US. So I am normally tweeting in the evening.
Really a good question. I type "when is the best time to tweet" on Google and there are so many articles answer this . Here is the link: http://www.google.com.vn/#hl=en&sou...aqi=g10&aql=&oq=&gs_rfai=&fp=52792e8fea567ff9 Personally, I often use Twitter in the morning or middle of the day, before my lunch. However, I think that it depends on your followers much. Especially where do they live.
Yeah! some time an earlier post re-tweeting allows new users and some existing users to attract towards the Retweeted Link