I think the closest analogy would be - the same way you're flirting with a girl. Like, if you know she's really interested you call the next day. If she's not then you "play hard to get" and wait the standard 3 days. You have to look at their indicators of interest, whether there's a specific timeframe involved, etc. Either way - it helps to follow up as much as every 1-3 days - you want to get the conclusion to a simple yes or no as soon as possible. Hope that helps!