as long as you are honest with this hiring mgr (the one who has shown interest in you), i can't see this interfering with anything.
however it may be different when interviewing for other positions.
i can't say whether it'll make a difference or not...
but since the terms of employment changed shortly after you started, to me, that is valid reason for leaving.
just have any prospective mgrs focus on your first job, where you have been for awhile.
that alone, should demonstrate commitment and maturity.
and yes, character references should account for something.
i would hope so anyways.
best of luck and keep your head high.
you'll be fine.