"At the end of seven years ..."

What does it mean when Deuteronomy 15:1 says 'At the end of seven years ...'? 

Does that mean that shemittat ossaph and shnat sheviit happen at the beginning of the seventh year while shemittat kesaphim kicks in at the end of the seventh year? 

It could be the difference between the former and the latter is that shemittat ossaph and shnat sheviit revert after the seventh year to their prior conditions whereas shemittat kesaphim is permanent.