Is it possible to add a delay before each thread executes?

Also interested to know how to do it to lower the intensity the requests for remote server. Please, advise.

yep, that would be really handy - any clues?

would balso be great to know how to send each request through a randomly selected proxy.

Is there a solution for delaying each concurrent threads without all the rest of threads waiting for the delay to finish? When I included the delay in the callback function, all the other threads also grinds to a stop.