There isn't really an option for that.

The thing to try is 
Connection 1
Max Connections per Second .3

I.E. one connection every 3.33 seconds

If Max Connections per Second does it's thing at the end of a file it would do
what you want, if it starts counting at the beginning then it won't. I don't
know how its coded so you will have to try it out.

good luck