I can only go by DH and I, when we first met.
We met at a friend's house on a Saturday night.
He called said friend on Sunday to get my phone #, which said friend provided, and then immediately notified me that he had my phone #.
He called Monday evening. I was out.
He called Tuesday evening. I was working.
He called Wednesday evening. I was working again.
I called him Thursday AM at work, and we went out to lunch that day.
As we parted from lunch, he asked me out for Friday evening.
As we parted from Friday evening, he asked me out for Saturday evening.
And so on.
I am of the opinion that if a gentleman is interested in seeing you again, he will make his interest known within 2-3 days of meeting you.
I never called guys until I was pretty sure there was mutual interest, meaning that for the first few weeks of the relationship, I pretty much let him lead in terms of calling. I would certainly return calls if he called and I missed him, but I would not initiate a call to express my interest in him.
I guess I am old-fashioned in that respect.