When is the best time to ask a girl out ?

Like in the starting talking state

When you start talking almost everyday

When you massage and call eachother

When you are comptable taking about sex and other things

When you are starting to drift apart

When you talk less but are still comfortable when ever you meet

Or when she start referring to you as her best friend

In my case i didn't have any feelings in the start but when we drift apart and she made me her best friend. i started to slowly like her and an consideration asking her out but we don't meet any more but talk sometime online