I found that a good way of figuring this out is to go to either the series homepage and see if they have DVD release dates, or go to Amazon for the same information. Also you can compare the release dates of previous seasons and get a pretty good idea of how that particular production company is handling it. I did this for Bones and they were regularly releasing the last season in October, like clockwork. I bet each production company has their own unique strategy for DVD release dates.
Now when any series will arrive at Netflix is a business deal between the series owner and NF. It all depends on the money. Sometimes you can find out from HackingNetflix, sometimes from NF itself, occasionally here (especially if it is a popular show with its own group - search groups, but that's a long shot.)
Hope that helps.