It was my mistake, I didn't realise that RTP would immediately cookie you and therefore not show you changes, so by opening up a new Incognito window I was then able to see the changes.
Save the RTP campaign, clear your cache, refresh your browser and you should see the campaign immediately,
If not, it sometimes takes a few minutes to be updated on our CDN (Content Delivery Network). So, it may take a couple of minutes, to initially launch and go live.
Good reply, most of the time it's the cache/cookie.
I've noticed that by deleting a few specific cookies I can trigger the campaign to load the new content.