I would like to explain how to use the Sugro when unpacking. It comes ready to use? And how long it can be exposed in the air before getting hard?

When you unpack Sugru it's best practice to knead it for about a minute. It makes the Sugru softer and easier to mold. That's all you need to do to get it ready to use.

The safe exposure time to air before curing starts is about half an hour, but kneading it now and then again can stretch that timeframe. I did that when I worked on a big project and the Sugru stayed workable for I think about an hour.
So you have at least 30 min. to work with it.

You also get a nice booklet with the Sugru package where you find the necessary help and a lot of nice tips, too.