This is false. The word itself does not imply one way or another how long after. You obviously made this up without even researching what the word means or else you would have provided example to back up your claim.
Genesis 30:19 Leah conceived again and bore Jacob a sixth son. 20 Then Leah said, “God has presented me with a precious gift. This time my husband will treat me with honor, because I have borne him six sons.” So she named him Zebulun. 21
Some time later ('aḥar) she gave birth to a daughter and named her Dinah.
Notice here that it talks about Leah giving birth to a sixth son that she had with Jacob. Then it says "Some time later (
'aḥar) she gave birth to a daughter". So, it obviously had to be at least about 9 months later after Zebulun was born that Dinah was born. Unless, they were twins, but there is no indication of such. In Barnes notes on this verse he said "Dinah" is the only daughter of Jacob mentioned
Genesis 46:7, and that on account of her subsequent connection with the history of Jacob
Genesis 34. Issakar appears to have been born in the sixth year after Jacob's marriage, Zebulun in the seventh, and Dinah in the eighth.".
Since I wouldn't be surprised that you would try to argue that Dinah was Zebulun's twin, I will give another example where the Hebrew word is used and doesn't mean right after.
Leviticus 25:15 According to the number of years
after ('aḥar) the jubile thou shalt buy of thy neighbour, and according unto the number of years of the fruits he shall sell unto thee:
In this verse the word is used to refer to something that was to be done "years after the jubile". So, years after is obviously not right after.
I'll give one more example and that should suffice. The word is sometimes used to refer to someone being behind someone else or something like that and is not always used in relation to time. And most of the time when used in relation to time it doesn't specify how much time after or give any indication if it's a short or long time after.
Deuteronomy 31:29 For I know that
after ('aḥar) my death ye will utterly corrupt yourselves, and turn aside from the way which I have commanded you; and evil will befall you in the latter days; because ye will do evil in the sight of the Lord, to provoke him to anger through the work of your hands. 30 And Moses spake in the ears of all the congregation of Israel the words of this song, until they were ended.
Here, the word is used to refer to something that would happen some time after Moses's death. Not immediately or right after, but something that he knew would eventually happen some time after he died.
So, now that you know what the word actually means, will you take another look at Daniel 9:26 with that understanding?
In other words, you like to interpret everything as if everything is meant to be taken literally, so that no real thought or spiritual discernment is required. Just like Paul said we should do, right? Or not.
1 Corinthians 2:14 Now we have received, not the spirit of the world, but the spirit which is of God; that we might know the things that are freely given to us of God. 13
Which things also we speak, not in the words which man's wisdom teacheth, but which the Holy Ghost teacheth; comparing spiritual things with spiritual. 14
But the natural man receiveth not the things of the Spirit of God: for they are foolishness unto him: neither can he know them, because they are spiritually discerned.