Before $time

[MN]

Hello,
I don't always know how much time my script is going to take, so I 
started writing a function that do "this" before a certain time and 
"that" if the time has already passed.
Currently the "this" and "that" are hibernate and suspend.
For example; if the time is set to 16:00 and the current time is only 
15:59 or less then it should hibernate the system.

There are two questions.
1) How should I compare the two time values? I think my approch is bad.
2) How good is the rest of the script?

local d                                                                         
                                                            
d=$(date '+%H:%M')                                                              
                                                            
                                                                                
                                                            
if [[ "$d" -lt "$1" ]]                                                          
                                                            
then systemctl hibernate                                                        
                                                            
else systemctl suspend                                                          
                                                            
fi