Lazyload an entire Bootstrap carousel

Long time reader, first time poster.

I have recently started learning to use bootstrap.

I am stuck trying to get the a Bootstrap carousel to lazyload (or similar effect).

I have pieced together the effect I'm going for, my first four images 'flick through' and the carrousel stops on my final image – but what I can't manage is to have the entire carousel lazyload before the carousel starts.

I've looked at lazysizes (by aFarkas on Github) – but I can't [even] make this work.

This is my work in progress – http://ift.tt/1DSImmJ – I'd like the carousel to show a 'load in progress' before it starts, like it does at this http://ift.tt/1OT63Pe as an example.

As is often the case when I'm learning my way around these things, I think it might be that I am missing something simple – is this the case?