When is it acceptable to ask ur crush out

Like idk im pretty new to this stuff. I never rly pursued a crush cuz i was afraid of rejection. But this one's actually in my friend circle. I'm pretty sure i decided i have a crush cuz i find this person attractive. But that's it. I don't know this person like on a deeper level and i only have a crush cuz of physical atttributes nd idk feel kinda ashamed of that. Feels im kinda forcing it tbh but at the same time im desperate for a relationship. At what point can i actually ask them out. After what stage. Do they need to like me back too? What are the signs i should look for.