How do I tell the boss I have new job?

Im in a pickle. When I first took my current job, my boss said will you come to me in 12 months and say I need more hours or your changing jobs. At the time I said no because I thought I would be able to support myself and get my own home business off the ground.
It didnt go as well as I hoped and now I need another job. Ive been in my current job 12 months and he is a really good boss as we seem to be on the same level. I waited till after xmas to tell him, now i have about 2 and a bit weeks till I start new job. The worst thing he said on Monday he going on holidays in the new year and he thinking of taking extra time off.
Oh Im going to hate this I just know it

So should I let him know when I start today, and work along side him for 6 awkward hours with possible silence? Or towards the end of the night, or right at the end?

Tell him verbally that you're leaving as soon as you can, followed by an email/letter. There is no way you can avoid the situation. If you really want to look out for him, give him as much time as possible before you leave so that he can look for a replacement. You don't want to burn your bridges by doing it the last minute and leaving him out in the cold. Even throw in the "maybe if we find a replacement before I leave, I can help train him/her"...you most likely don't have to, but it's a nice offer to give.

It's not that personal, people come and go all the time. You're not breaking a contract or haven't done anything dishonorable. He'll understand career opportunities and wanting to move on.

stop showing up

Well, there's no way to tell him that will make him happy. So next time you see him, say something like "I know this isn't going to make your day, but I'm going to be leaving in a couple weeks". Follow up in writing with your end date specified in the letter.

Give your two weeks notice and tell them your moving on. That easy.

You have to do what you need to do. It might not be easy. Hey, he even predicted it would happen. Jobs come and go.

Just let your boss down easy, like say that you have found a job nearest to your home ; and that if he/ she needs any help you'll love to help out when you are off without pay! It's not easy switching jobs, just make the best of it.

Just let him know that you have a better opportunities and this is your 2 week notice. He definately deserves a notice!

Put in 2 weeks notice and tell him it was a learning experience and you enjoyed working with him you but you are going to pursue you dream of owning your own business.

If this job is not paying enough to support yourself, then it is generally no big loss to the company that you work for when someone up and quits. It sounds like you should be more worried about the person that is going to have a hard time paying their bills than the person that owns their own company and can replace someone with a single phone call.

You should prepare a letter indicating the 2 weeks notice. Your boss will respect you more if you are professional in leaving, instead of just waiting until the day you leave to tell him.

Just tell him your situation changed and you have a new job and goodbye. Offer him a week's notice and then leave. Why are your feeling badly about this, if it were the other way around and he decided he didn't need you to work there anymore do you think he would have any second thoughts, or compassion for you? It's business, don't make it personal because he would think of it as business.