I'll be receiving presents for 180 days before and after my birthday.
You can give me presents either 180 days before or after my birthday.
ーI'll be receiving presents for 180 days before and after my birthday.
誕生日の前後180日はプレゼントを受け付けています」
○ days before and after ... で「…の前後○日」
ーYou can give me presents either 180 days before or after my birthday.
「誕生日の180日前か後にプレゼントを受け付けています」
either ○ days before or after ... で「…の前か後○日」
ご参考まで!