When I try to refer find command's man page , I come across -mmin n        The value of n can be one of the following:          n               Evaluates as True if the file modification time subtracted from the initialization time, divided by 60 seconds (with any remainder discarded), is               n.          -n               Evaluates as True if the file modification time subtracted from the initialization time, divided by 60 seconds (with any remainder discarded), is               less than n.          +n               Evaluates as True if the file modification time subtracted from the initialization time, divided by 60 seconds (with any remainder discarded), is               greater than n (in case of UNIX03, greater than n+1).        Note: Files modified after the find command start time will not be taken into account. However, when the find command is used within the unary NOT        operator for non-UNIX03 behavior, the files modified after the command start time will be displayed until the value of n.   -mtime n        The value of n can be one of the following:          n               Evaluates as True if the file modification time subtracted from the initialization time, divided by 86400 seconds (with any remainder discarded),               is n. 86400 seconds is 24 hours.          -n               Evaluates as True if the file modification time subtracted from the initialization time, divided by 86400 seconds (with any remainder discarded),               is less than n.          +n               Evaluates as True if the file modification time subtracted from the initialization time, divided by 86400 seconds (with any remainder discarded),What is this initialization time? Is this the time when find command got invoked? 
What is the initialization time in the find command?
shell;find
Yes. The initialization time is a particular time after the find command starts and before it starts processing any file. It's a common time origin, to avoid the outcome of time-based comparisons to depend on the order in which files are traversed.Initialization time is the term used in the POSIX specification. FreeBSD calls it the time find was started. GNU and Solaris don't document it but also use a time origin.