one year earlier

[Dr.Appalayya]

First and foremost, my family had scheduled my Mecca trip one year earlier, by which time we never had any idea that it would clash with my exam.

Are the phrase in red letters correct ?

 

[Dimcl]

First and foremost, my family had scheduled my Mecca trip one year earlier, by which time we never had any idea that it would clash with my exam.

Are the phrase in red letters correct ?

Here's what I might say:

First and foremost, my family had scheduled my Mecca trip one a year earlier ago, by at which time we never had any no idea that it would clash with my exam.

 

[volky]

If you want to keep the same sentence, I suggest the changes in green.

First and foremost, my family had scheduled my Mecca trip one a year earlier ago, by at which time we never had any no idea that it would clash interfere with my exam.


Otherwise, I suggest:

My family had sceduled my Mecca trip in advance last year, when we didn't knew the exam schedule.

(I don't know the rest of your text, but I don't like the use of first and foremost, because it sounds intimidating, especially if you want a professor to excuse you due to a trip planned in advance.) Just my opinion....