IF function with dates

Hi - I have a spreadsheet keeping track of dates training courses are completed - I am trying to include the IF function to add a tick if the date the course was completed is before the due date, but I want the cell to stay blank if no date is showing in there.

I'm using =IF(G6<DATE(2020, 09,15),K2,"") - K2 shows the Wingding tick to be put in the cell once a date is added to G6 but it's also showing when there is no date in the cell - how should I be wording my formula to only show a tick when a date is added to the cell?

Thanks for any help