You're going to get a lot of blowback on this site for testing SN, fair warning. Most people tend to think its just stupid, and to be totally fair, the benefits of doing it are questionable. The effects of a sub-lethal dose and a lethal one are likely to be two different experiences entirely. I mean...one kills you, one doesn't. That said, if you're going to do it anyway...
"..like i want to drink three pinch of sn..."
Stop here. Bad idea. The LD-50 (dose that is lethal 50% of the time) starts at as little as 4g, for small people. 5g of SN is roughly a teaspoon - that's not a lot. So you need to be a hell of a lot more accurate with your weights and measurements than "pinches." This stuff is nothing to fool around with, it is a lethal poison which is why its popular among people looking to ctb. If you're not ready to ctb, the best policy is don't take any at all. But if you want to push the envelope and try it anyway, you need to be a lot more precise.
You can potentially feel some of the effects you can expect with a lethal dose without taking enough to kill you, but in the end, its just questionable how useful this exercise actually is. I can't tell you to do it or not to. What I can say is you should fully understand the poison you are taking and how it might affect you before you play with it like a toy. There are many resources on SN here and elsewhere on the internet, I suggest you explore them thoroughly before making this decision. Best of luck, be careful.