Seriously, #TimeTravelAuthors --nobody has absolute control over which page any given reader has the power to begin at, so how about you index each time you've used the word "meanwhile" to refer to multiple concurrent events in your story's "timeline"; timelines exist to establish sequence of events and "meanwhile" indicates an event that is necessarily NOT subsequent to the previous event but is instead concurrent. Same condition exists when you use the term "previously".
Then consider the nuanced differences between "time" and "timing".
Now go write.