There is no one-size-fits-all when working on a game launch.
Here are some proposed deadlines for the larger tasks when getting ready to launch your board game.

6 months before launch date:
Create a landing page to capture emails and ensure this is linked to an email service provider

Determine your budget and ideas for your marketing plan.

4-6 months before launch date:
Continue to playtest and finalize your game and your rules, especially through blind playtesting.

Finalize art and design for your prototype.

4-5 months before launch date:
Determine potential stretch goals and deluxe version ideas.

Finalize your components and get multiple manufacturing quotes (from at least 5 manufacturers), including line-item breakdowns and separate quotes for the base game and anything else you are considering (deluxe version, stretch goals, etc.)

Finalize your rulebook.

4 months before launch date:
Order prototypes of your game for reviewers, etc.

Create a very preliminary Kickstarter page and get your project approved so that you can start asking potential backers to hit the notification button on your page.

3 months before the launch date:
Hire a videographer to create your Kickstarter video, along with any teaser videos or GIFs that could be used for your campaign.

Research potential reviewers and previewers to find good matches.

Research and reach out to fulfilment partners for shipping and fulfilment quotes.

2 months before the launch date:
Determine your preferred manufacturer and fulfilment partner(s), along with backups for each.

Finalize your pricing model for pledge levels, funding goals, and shipping by region. Get feedback on the pledge levels from members of your Facebook group, they might have other ideas that you should take into consideration. 

1 month before the launch date:
Ask your manufacturer for an updated quote that will still be valid when you enter into manufacturing.

Research and determine which pledge manager you will use.

Develop and review your FAQ sheet.

2-4 weeks before launch date:

Notify media outlets

1 week before launch date:

Finalize your Kickstarter page and all remaining details.

3 Days before launch:

Hit your email list with a notification that your project will go live (insert hour slot with timezone).

1 Day before launch:

Ask in your Facebook group who is going to be backer #1. This creates friendly competition and highlights the importance of being early.

1 Hour before launch:

Ensure that the newsletter goes out to everyone on your list, notifying them of the launch.

On launch day:

Hit the launch button at the time of launch!

Should you have any questions or need help with these tasks, feel free to reach out