preposition
in the beginning of july or at the beginning of july
in the end of quarter or at the end of quarter
in the end of year or at the end of year

keep doing something : can i say- " i will still check it everyday" or " i will continue to check it everyday" or

Question

preposition
in the beginning of july  or at the beginning of july
in the end of quarter      or at the end of quarter
in the end of year          or at the end of year
   
keep doing something : can i say-> " i will still check it everyday" or " i will continue to check it everyday" or

Answer

For the in/at questions, either "in" or "at" can be correct. It depends on what you want to stress.

"At" refers to a specific time, At 3pm, At lunch, At the moment. So you can say "At the beginning of July" if you want to stress that specific point in time.

"In" refers to a non-specific time, or a duration of time. In July, In 2010, In the past/future, In the end. In daytime. So "in July" an means very much like "during July": In the beginning of January = During the beginning of January.
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It is the same for "in/at the end of the quarter" and "in/at the end of the year."

As for "on" in prepositions of time, "on" refers to a (specific) day or date. On July 4th, On Christmas, On Saturday(s), On my birthday, On vacation/holiday.

Answer

at the beginning of July
at the end of quarter
at the end of year

You could say both of those things, they both make sense