unclear and makes no sense, let alone the fact that it sounds impossible for anybody here to answer. where do people get these questions? Twitter is good marketing if you have followers that actually want to read what you've got to say. naturally this does not fit all sites and demographics. test the waters, thats all i can suggest.
I would say around 6-9pm Eastern Standard Time, since twitter is marketed mostly in America and thats the time most people in the US are online. And, its when I see the highest number of tweets.
thanks MM, That's what I thought too, I see a little bit of activity before people goto work in the morning too but not like the P.M. thanks again
twitter is full on 24 hours a day many ppl twitter at work, at night and than you have everyone on the other side of the word you can see I update between noon and midnight http://tweetstats.com/status/vbsetup
Typically later in the day, however, with the growing user base, you can find Twitter activity pretty much any time of the day.
It depends on your followers geographical status. If most of your followers are is from China and India, I think office hours during GMT+8 time will be the best.
Atniz is right, it does vary according to who you choose to follow. But in my case I am from the UK, and I often find the best 'action' going on after I've gone to bed... that's after about 11PM GMT. I have come to the conclusion that most the people in the US/ Canada are online around 6-9pm EST like MMandYou mentioned.