Honestly think people should play ranked ASAP and just go in with the expectation that they are probably bronze at first, and low bronze at that. The first couple dozen games might be quite rough as a result as you fall from mid silver elo to your 'true' elo, but it's a lot easier to gauge your skill when you're reliably playing against similar mmr players (instead of the very mixed mmr matches that normals commonly presents), plus everyone is trying hard in ranked so it's a more 'real' test of skills, and potentially a better environment to actually get better.
That said, play a ton of normals and see what the average rank of your opponents tends to be. If it's silver+ and you're doing ok in those matches, you're probably silver-ish at least.
If you're not playing support/jg, try to get an idea for what your typical cs/min is. I'd probably aim for at least 5cs/min if the bar is 'only' silver, although keep in mind 5 cs/min is still pretty bad in absolute terms so if you're keen to improve practice that until 7+ cs/min even under pressure is second nature.
edit: Looking at your op.gg a bit, I'd probably say you're bronze 4 or bronze 3 ish material currently. This is a fairly normal skill level to be if it's your first account, the trick is to always be looking to improve. Whenever you die try to figure out why, try to work on your csing, map awareness, and so on.