You can start speaking with a native speaker whenever you feel comfortable. You can speak with a native teacher at any point, the sooner the better.
Regarding speaking with panthers, I wouldn't recommend it. They are unreliable conversation partners. I think that is the word that you probably meant to say -partners
I don't see that as a level, I say it because I know so many people on advanced level afraid to speak, people that spent most of their time on books and grammar.
I was already practicing my italian on my 3rd month of study, even making a lot of mistakes I like to put what I have learned right away.
So as long as you feel ready, start doing it.