She's text back after 3 days, do I reply straight away or leave it a while and make her sweat it out now?

Anonymous
Obviously I don't want to blow my chances and leave it too long that she may lose interest, or then again don't want to seem too keen. So is it best to reply a few hours later or couple of days like she made me wait?
What do you girls think?
Updates
+1 y
She has agreed to come for a drink with me, if this changes anyone's answer
She's text back after 3 days, do I reply straight away or leave it a while and make her sweat it out now?
6 Opinion