When I was doing OLD, I generally asked for a meet up pretty fast, sometimes without even asking for the number. It helped weed out the chick's who were just looking for orbiters or an ego boost. I think the know within a few messages whether they are going to boink you or not.
Occasionally one would say "that's a little fast, I would like to get to know you better first" and I would say something like "can you really get to know someone online? I think we can learn more about each other in 30min over coffee than a thousand text messages".