Delay before loading data

Hello.

In our current project we have got a request from client: to set a pause before starting data loading. Because, with fast internet, a data appears very quickly and sometimes user can't understand what happened.

I just add a new parameter `delay`, which equals 0 if it isn't set.

Maybe it isn't the best solution, but I tried to share our use case. It can be useful not only our client.

Thank you for your job!