One way of doing it is creating a VF Page say "StartUp page" and assign it to a visualforce tab say "Startup".
Now go to "Apps" list and say you have a custom app say "Recruiting" click on it and you will land on it's detail page , there click "Edit" button where you have an option of selecting the "Dafault Landing Tab" in that list select "Startup".
Please be careful about the visibility of the "StartUp" tab to the requisite profiles.
Did this answer your question? If not, let me know what didn't work, or if so, please mark it solved.
One way of doing it is creating a VF Page say "StartUp page" and assign it to a visualforce tab say "Startup".
Now go to "Apps" list and say you have a custom app say "Recruiting" click on it and you will land on it's detail page , there click "Edit" button where you have an option of selecting the "Dafault Landing Tab" in that list select "Startup".
Please be careful about the visibility of the "StartUp" tab to the requisite profiles.
Did this answer your question? If not, let me know what didn't work, or if so, please mark it solved.