Ask HN: When to start a startup?

I am a current college student and I want to get my friend to start an idea with me. I am asking the HN community on when should be the time to start it? I also have experience working at two previous startups and I know I want to make my own now.

I have a few questions, how would I go on finding an advisor and should I plan to move to california during the summer?

Any help/advice would be appreciated or contact me through my email.