As early as you can learn to be mature about criticism, the better. You’re gonna read this again and again here, but this business is not for spoiled wimps. You have to be a Gladiator. 

You know what they say -- that you are the average of the three people with whom you spend the most time. So:

Here’s a cautionary tale: So, I was at Wesleyan, beloved alma mater, as part of a weekend workshop on film & TV. As part of that weekend, students were able to come up with feature ideas and pitch them to an alumni who heard pitches for a living at a big studio. Henry Hipster led his team in pitching a feature idea. It was, any sane witness would agree, crap. The alumnus was quite gracious about pointing out its limitations. Later, I heard Henry Hipster on his cell phone, whining to someone that Alumnus’s reaction was bullshit because Henry's mom had heard the idea and his mom thought the idea was dope. 

Oh, Henry. Your mom liked it, did she?

Find people who will read your work and give you THE REAL. And be grateful to them. Be humble enough to buy them a meal and thank them for trying to make you a better writer. And do the same for them. And bring that attitude into your career when you are getting paid by people who are getting paid to give you notes. 

A team wants to give you the real so that you can lift each other up (the exception to this is Lance Armstrong, who did not really help his team really in the end now did he?). An entourage kisses your ass and does not help you. And the third alternative, lobster friends... Lobster friends are scared and small-minded, and if you try to get out of the tank toward your dreams, they'll pull you down. Lobsters are for eating. And that is all.