Must I use past tense before 後?


From [this
page](http://www.guidetojapanese.org/learn/complete/verb_sequences), I see
this sentence:

> **Note** : Be careful of the tense of the verb that comes before 「前」 and
> 「後」. 「前」 is non-past while 「後」 is always past tense.

I am confused because it is quite weird to disallow the usage of non-past
tense before 後. What if I'm talking about the things that I will do tomorrow?
For example, which should I use if I want to say "I will go to school after I
have breakfast tomorrow"?

> 明日は、朝ご飯を食べ **た** 後、学校に行く。
>
> 明日は、朝ご飯を食べ **る** 後、学校に行く。




This た doesn't mean "past" but "completion". It isn't unnatural that た which
means "completion" is used in things in the future.

So 明日は、朝ご飯を食べた後、学校に行く is correct.




This た doesn't mean "past" but "completion". It isn't unnatural that た which
means "completion" is used in things in the future.

So 明日は、朝ご飯を食べた後、学校に行く is correct.

