This function requires a date or timestamp parameter. If using a date with spaces, be sure to wrap it in quote marks or it will fail.
This function is especially useful for opening or closing sections of your site automatically:
[if after 'December 02, 2021']Enrollment opens soon...[if]
Note, in the case above, the conditional above, it compares the current time with the "beginning" of December 02, 2021 not the end. If I wanted the condition to start after midnight, I would use next day for my parameter, or I could add the 23:59:59 to the time parameter.
Note this uses the strtotime function in PHP so you can do things like
[if after 'Friday']Enrollment closes Friday...[if]
However, note the condition will reset the following Sunday, as PHP now assumes you mean the current week's Friday. And this may not be the desire you intend.