Your third example provides the greatest chance of the user clicking without the override handler having been attached. The browser generally downloads and parses each before moving on to the next. You're pulling in jQuery from an external source (Google) -- which, while likely reliable, could be unavailable or slow to load. You've got both blocks at the end of your document , so previous areas of the page will probably already have been downloaded and rendered to screen while these last two scripts are handled. While this approach is advocated to present a responsive page load experience to the user, they could click during this uncertain period, and of course the override handler would not yet have been attached.
There's an interesting YUIblog article on scripts and load order here.