2 Days?

Over the weekend, I didn't hear from Heidi at all even though I called her on both days. Usually I would think that would be too much, but she typically returned my calls on the same day. I had just asked a friend how long she thought I should let a phone call go unreturned. She said two days. That's it? Is that the general concensus? It just seems so short. I was just beginning to like this girl and now I get to find out that she's not interested in me. Is this how dating is supposed to be? I've gone one two dates with the last few girls I've met and now they've fallen off the radar.

That leaves one left.
I don't think I ever wrote about it, but a few months ago I went to a friend's birthday party/drinkathon. Near the end of the party I chatted up a short girl with big bangs. I'll call her Dana. Unfortunately I drank too much and forgot to ask for her number, or so I thought.
Over the weekend, I added her on Facebook (yeah, I know), and asked if she'd want to meet up some time. No response. Not a huge deal, just another pretty cute girl.
Then comes last weekend when I got a call from the birthday friend (Kyle) telling me to go to a party in my neighborhood.
Well what do you know? It's Dana's apartment. And it's a Tom Selleck party, moustaches everywhere.
After saying hello, I kept the chatter to a minimum since I was still embarrassed about being the drunk guy hitting on her last time.
Near the end of the party, people were starting to get to some bars. Kyle went home with his girlfriend, so I thought it'd be a good idea to go home also.
As I was leaving, I decided to ask for Dana's number. I said "Dana, I'm just going to say it: I think you're really cute. Could I give you a call some time?" To which she replied "Um...you already have my number. And I have yours. See? I'll call you right now." What??? Is this for real? I was that drunk?

10 seconds later, my phone is ringing. Phone number's tagged as "[Someone not named Dana] Kyle's Friend." So apparently I've been sitting on Dana's phone number for two months without knowing it.

So that's the scenario. I'll try calling tomorrow to see if she wants to grab a drink. If not (meaning she lets the phone go to voicemail and doesn't call back), then I'm back to nothing.

What do you think about the Two Days guideline? Is that a reasonable amount of time to give someone to call back? Personally, I return calls that day if I'm interested and it's not too late. What about you?