Hey Patrick Ledesma,
In playing with Tableau Server and tabs I have found that the best way to assure your user is reaching the desired tab, is to share the link that pertains to the tab. I navigated to a dashboard I created then sent a colleague this link:
When they entered their credentials, they were taken to the desired dashboard.
While there is no set way to to specify a "default" tab, I would recommend up-voting the following feature request, and encouraging others to do the same:
I hope this helps :-)
I don't think this solves your issue and having a "default" could be nice but on Tableau Public at least I've noticed that it pulls up the tab you had active when you last saved the workbook before posting. So if you have the Executive Dashboard up when you save the workbook and then post it that should be the view that comes up for everyone. I have no basis for that statement other than what I think I've noticed on Tableau Public.