Hi,
Are these timings shown immediately on the very first page of your publication? Though I found no problems in performing a test EXE, it can sometimes be beneficial to appreciate that Opus is 'loading' the pub, so the very first timing events are taken into consideration. You simply can design these accordingly.
See attached IMP that shows a more rigid way of timing using the On-Hide Action, plus another example showing the use of a simple Timeline. (both accomplishing what you desired in your timings)
Hope this helps.