Have dabbled with the supers last yr before my break from the scene. Personally found half a tab would edge you out for a whole session (45-60min), definitely stopped me from finishing quickly. Was good for PSE sessions. For me the tab benefits lingered around for around 12hrs, good for a late night and early sess next morning.
A good balance for me was quarter or a third tab. No side effects (different story with half and full) and good for 30min sessions. Tab effects only lasted for 4-6hrs.
Regardless of dosage size, the tabs kicked in after about 1hr for me.