Prior - Is your first slide 'Pre-setup'?

You may be a natural-born public speaker, but you will not be able to 'wing' a presentation. Setting up a presentation takes time and practice. You want web pages already open, you want VMs ready and demos good to go.

So document the steps to undertake before starting and you will present in a snappier fashion and not need to say the lame statement "hope the demo gods are kind to me today".