1) What are the best times to approach press prior to the release of one's game?Just as one of the posters already indicated, once you have something of value to show. Journalists, Let's Players and Bloggers are usually contacted multiple times during the time. Some famous journalists get between 300-500 requests per day. They don't want to post screenshots or patch notes, they want to see content that is playable and enjoyable for their audience.
2) Now that my game and the promotion materials (trailers, screenies, etc) are ready, what should be my timeline from here on for the release?Before you contact the press make sure you have a press kit ready. You can easily create one for free, which has an industry accepted template here:
http://dopresskit.com/The press kit that I linked above contains all the information a journalist / blogger / Let's Player needs. It contains screenshots, a trailer and additional links that might be interesting for them.
3)The VERY FIRST email we send to a website is what determines the fate of the game for on website. What should be the contents of that email? Should be a direct mention of the game, some details and a press release link? Or should the developer first have a word with the journalists and then send the details?When you are releasing your game on Steam, ALWAYS include a Steam product key when you contact large websites with big communities. You don't want to keep e-mailing with them or let them ask for a review code. The content should include a simple but catching title, a link to your press kit as linked above and a brief statement. Also include additional contact information. Don't forget to also mention that you are open minded to setup contests/events, do interviews and/or help them with anything else.
4)If one should talk to the journalist first, then what should the email be like?There are many examples on the Internet with DO's and DONT's. Also, don't send a general e-mail but invest some time and effort in it. Personally address them, perhaps follow them on Twitter or other social media. You want to build a lasting relationship, also for future products that you are planning to release. If you become 'professional friends' with them they are most likely to publish content for your game on their channels.
Hope this helps you on your way.