Would the sentence below make sense?
You would say
I would usually use
後｛ご｝, as an indication of what is to come :
Another example :
Maybe you also know
後｛あと｝で as a way to say,
afterwards, in a while, this is the same kanji. You can use it this way :
You could say
Or a slightly more formal
I asked my Japanese teacher about this (as it came up somewhere else) the following clarification was made:
BAD: 後２０分に (This phrasing is typically used for an ongoing action that has already started)
GOOD: ２０分後に (This specifies a time point in the future)
I have edited the answer accordingly.