1. Just do it.
2. Dont be afraid to touch them lightly (shoulders etc). It sets a good tone, and gives you confidence when you notice them reacting.
3. Just do it.
4. Be a man. Do it.
5. Just – do – it.
Catch my drift? I think the mistake i used to do was overthinking it. Don’t think too much about it, if you think it’s time, dont let your questioning mind get a foot in the door, and just do it. If you try to soon – no harm is done and she will let you know either she’s not interested or not ready – no problem, (back off, don’t be an asshole, and dont take it like an asshole, just keep conversation going like nothing happened).
Now she knows you are interested too and it’s not a big deal if she said no, she knows what you want and you’ve proven you can take the initiative – nothing to be ashamed of (wow, big surprise, you are interested in girls. I don’t know why i used to be so scared of showing girls that i liked girls – it used to be a big blocker for me, i dont know if it’s a problem for you too).
If you try too late – she will already have written you off. You see there is a time window. If you try too early, it’s no biggie, but if you try too late – the door is closed forever.