3 day rule

I remember learning from some late 90's chick flick that you have to wait 3 days after meeting someone to call them. I've never personally followed this rule. If I like you, I'm texting you 20 minutes after I get your number. If you like me, you're doing the same. I assumed my practice of this was because if it was meant to be, it'd be that way now or later. I've learned otherwise. 


My phone rang a few minutes ago. The number calling was saved in my phone. It was a boy's name. I do not know anyone by this name, but I know I saved this number. I checked my text messages, to see if I'd ever had a random text-conversation with this person. No. I checked my call logs to see if I'd ever talked to this person. No. I looked up the area code on his phone number to see if I could remember meeting anyone, ever, from that area. No. Thank goodness he left a message. 
"Hey L, haha, I like your voicemail*. It's P, incase you don't remember, I met you Monday at ****. I was just calling because I had a great time talking to you Monday and getting to know you, and I was wondering if you'd want to go to dinner tomorrow or Saturday....." 


*My voicemail prompt says "Leave a message". People have told me I sound pretty angry. I don't really like listening to voicemail, or leaving them. 


He then told me his schedule for the day, so I'd know when to call him back with an answer. 


THANK GOODNESS he left a message. The guy would have had no chance of a call back otherwise. And THANK GOODNESS he identified himself, when we met, and where we met. He may not have known it, but I was there doing a job interview. The person interviewing me was taking shots, and buying them for me. I remember meeting P, but I didn't commit enough of him to memory to have known his name. 


The 3 day rule makes some sense. You don't want to seem too eager, and I get that. You still seem interested enough when you call 3 days later. (You're still thinking about me 3 days later? That's almost more enticing than a call 20 minutes after the number exchange.) But boys, pay attention to what P has mastered: leave your name, when you met, and where you were when you met. Maybe even how you met. Be complete. Otherwise, you're just a creep who took my phone and entered your number, since I have no recollection of writing it down myself. 


Class dismissed. 
L