I'm about twenty times more likely to do something if people say "Hey, wanna come over now?" (although I will usually take time to finish up everything I'm doing first) than I am if they offer it a day in advance. The further the invitation gets from the event the less likely I am to go. It also helps if you always offer an activity instead of just hanging out, even if its just watching a tv program or playing a quick game of cards. "hey, you wanna meet up today?" would work only for my friends, and even then not all the time.
i prefer when people specify what we gonna do, love it when it's some active stuff. " wanna meet up" or " wanna hang out" sounds like we gonna sit & talk about nothing for hours, which is not really my definition of quality time.
A few hours notice is enough for any kind of activity, for me. Usually I plan my work until the end of the day so I need a little time to rebuild those plans, divert stuff to other days, and prepare for the event itself. No notice is still fine, but there's more of a chance of me being quiet ISTP if I didn't have time to think about it.
Personally, a few hours. Spontaneity is interesting and also, having a few hours notice is actually better as I have a better idea what mood I'll be in by the time the event comes around. If I'm given days or weeks notice I have no idea if ill be in a mood to be around people at the time when I say yes.
I'm down with doing things day of, but I need a few hrs to get ready before I head out cuz I like taking my sweet ass time. When I'm bumming at home and my friends call me to come out to the bar "right now," they won't see me for at least another hr and a half
I don't like making plans over a day in advance, because then I have to have it looming over me and distracting me from my current situation. If someone calls up the same day and asks to hang out, however, I'm usually cool with it as long as I have time to shower and eat. Also, having too much time to think about how much I really don't want to go out and socialize makes me more likely to back out of it.