When meeting someone new, how long do you wait to call? Do you even wait?

I know this question is probably did to hell but I want your opinions – How long do you wait to call after meeting someone while out and receiving their number? Does the fact that they seemed pretty interested play a factor?

No one wants to seem obsessive so you of course dont want to smother someone immediately and wait – but how long do you wait so that the person doesn’t misinterpret that as a loss of interest?

Is it weird to just text the next day or two and say “What’s up?”