When should I start playing graves in ranked?

So I bought graves 3 days ago and i've been playing him non stop. I used to be a Zac one trick but after Zac became meta I realized I need to open up my champion pool just in case it happens again once he's done getting nerfed. I've been trying to learn Graves and i'm pretty trashy, My build is completely random, I try to AFK farm but I get flamed constantly. I'm currently Bronze 1 (I was placed Bronze 4 and easily climbed to Bronze 1 in a week but after Zac got reworked I decided to stop playing ranked because I'm not quite used to the new Zac.) FYI: I took a month break. So when should I start playing Ranked with graves? Once I hit M6? When I feel confident? I decided to go with Zac in ranked after I carried or had a positive K/D constantly in normals and I ended up going from a 25% WR to a 63% W/R (obv its dropped) But I really wanna start playing ranked again so any help would be appreciated. Also if you can hmu with a build