According to ENGLISHPAGE.com, if the Past Perfect action did occur at a specific time, the Simple Past can be used instead of the Past Perfect when "before" or "after" is used in the sentence. The words "before" and "after" actually tell you what happens first, so the Past Perfect is optional.
Specific time:
She HAD VISITED her Japanese relatives once in 1993 before she moved in with them in 1996. (Correct)
She VISITED her Japanese relatives once in 1993 before she moved in with them in 1996. (Correct)
However, if the Past Perfect is not referring to an action at a specific time, Past Perfect is not optional.
Unspecific time: Here Past Perfect is referring to a lack of experience rather than an action at a specific time. For this reason, Simple Past cannot be used.
She never SAW a bear before she moved to Alaska. (Not Correct)
She HAD never SEEN a bear before she moved to Alaska. (Correct)
Reference: http://www.englishpage.com/verbpage/pastperfect.html
My question is, is it the same way with Future Perfect and Future Simple tense?
Specific time:
By 11:00 am, I will + VERB(infinitive). (correct)
By 11:00 am, I will HAVE + VERB(Past participle). (correct)
Unspecific:
By this time tomorrow/By the time he arrives, I will + VERB(infinitive). (Incorrect)
By this time tomorrow/By the time he arrives, I will HAVE + VERB(Past participle). (Correct)