How far do you go with someone you like before you become couple?

Depends on how old you are really.

If you're a kid, like under 12 or something, if a girl even talks to you, you're basically already dating.
As you get older though you do more intimate shit before you date, so like maybe 14-16 flirting, 16-18 2nd base, and then when you're an adult you usually have sex with somebody you like (probably a few times) before you're "official".

If I like a girl then I will ask her out straight away which is what I did with my current girlfriend. For the couple of years before that while I was single I would always explain to girls that we would only be having sex and I wanted nothing more.

Honestly it just depends on the person. Recently I was "talking" to this dude for a few weeks and we flirted, made out, fooled around a little and that was it.

My last boyfriend (still kinda together? Its complicated) and I had an odd development... hung out a few times randomly through mutual friends. Went to open mic night, he came back with us.... we hooked up, did the fwb thing for a few weeks, then realised we're wayy past fuck buddies in how we feel about each other.

I don't think the development has hurt us at all, the fact that we're still (unoficially) together even after some disagreements just kinda goes to reinforce that.

It depends on the person. If I was comfortable and felt a connection with the person, I would go all the way. On the other hand, if I wasn't sure about him yet, I wouldn't go any further than the make out stage.

I feel like the kiss kinda leads into the dating. After you kiss it makes a little easier to ask "Are we going out?"

As an adult I've always fucked the girl in our seeing each other phase before asking her out.

You always test drive a car before you buy it, same principle to me.