In Squid Games, we see the policeman visit his brothers dorm room to find the business card with strange symbols. This leads the policeman to believe that his brother is a participant in the current Squid Games. But in the end we find out that his brother was missing for multiple years, rather than just a couple of weeks as implied by earlier episodes.
So why would the policeman's brother keep a dorm room after all these years? If it was for cover, why did he stop paying for it all of a sudden (the landlord lady mentions she'll clear it out soon for non-payment)?
In the second episode, Hwang Jun-ho has a conversation with his mom. He says that he will call everyone who might know where his brother is. He also adds that his brother dodges their calls all the time. Jun-ho says that if he can't find him by the next day, he will report the brother missing.
Since the brother hasn't been reported missing yet, it's safe to assume he has been missing only for a few days or a few weeks at most and not several years.