Question

I will be at home ........ Friday morning.You can telephone me then. preposition fill in the blanks

Answer 1

hey
ur answer is ....

I will be home BY Friday morning
• • •

Answer 2

I will be at home by Friday morning is the right sentence formation, so "by" is the right answer for the above question.  

You can easily recognize the prepositions here before only a few prepositions will be available for you to match this sentence.

Also, the time is the key element here so the answer can be easily determined.

Hope it helps!