no native speaker here and I am not entirely sure which one is correct.

This is what I am suppose to write:

> 
> IMPORTANT NOTE: The recommended minimum 
>  retention time of 60 minutes after check-in 
>  is reached on 16:30.
> 
> 
> 

This is how I would write it:

> 
> IMPORTANT NOTE: The recommended minimum 
>  retention time of 60 minutes after check-in
>  will be reached at 16:30.
> 
> 
> 

Any suggestions? I am also thinking of using "will be passed" here.

NOTE: This text is shown when the time has not passed yet and "16:30" will be in the future i.e. 10 minutes away from now.