How long does it take to rent an apartment?

First time renting an apartment, so bare with me.

I will want to move out in about six months. Should I wait until I’m actually ready to move out to apply, or should I apply a few weeks, or even a few months in advance?

Particularly if the apartment I want is a nice one, and in the Bay Area, so it’s very possible I won’t even get it?

And any other advice about this while you’re here?

Thanks.