Best Practices for audio/object start time?

So we have been using multiple elearning tools over 10 + years and delivered them through different LMS platforms over those years. We are revisiting our best practices for Articulate Storyline and have hit a stumbling block around "whats the best timing for the appearance of objects and audio"?

In the past, we added 1/2 to 1 sec blank space at the start of the slides timeline to allow for the page to load as we found audio at the start of a slide was chopped off as the slide would progress. 

This was the process publishing in Flash but now all is published in HTML 5.

Does anyone still do that today or have the same "lag time" on loading screen to screen?

Any other thoughts around best practices for when to start things appearing and being heard on a slide?

Thanks!