if the expired domain was good and indexed by google you should see improved rankings and / or improved authority (DR).
if the expired domain was good but it's not indexed by google yet you shouldn't see anything yet
if the expired domain was bad and indexed by google it should negatively impact your current domain too if you already ranked. If you didn't rank yet you probably can't tell yet that the expired domain was bad (unless you did proper research on it), but you'll be able to tell when nothing you do SEO-wise works
if the expired domain was bad but not indexed by google yet you shouldn't see anything yet