1) It gets dark at around 5 p.m. 2) It gets dark around 5 p.m. which one is correct ? Are both correct ? Am particularity confused about the usage of "around" and "about" in sentences where both seem logical.

Hi Souvik, the usage "around" and "at around" is a matter of convention. "Around 7 PM" generally means a few minutes before 7 to a few minutes after 7. "Free at around 7 PM" generally means free after 7 PM.

"Around" is generally used with time.