Welcome to the forum.
I have good news and I have bad news. Conditional formatting will work in your case, but the check mark is an issue.
Coincidentally enough, I was tinkering with this very problem the other day. One of the annoyances with CondFrmt is that the Font cannot be adjusted within the dialogue wizard. The Font Style (like Bold, etc), Underline, Colour and Strikethrough can be set but the Font itself and its Size cannot. This matters because the real checkmark comes from the Font called Wingdings2.
That column of dates is not text (at least, it shouldn't be). Dates are Excel Serial Numbers --- they are not text. In any event, I gather that you want a check mark if there is anything at all in the column. We can fake it one of two ways.
One) 1) Format the entire column or relevant range as font Wingdings2. 2)Select the entire column or relevant range. 3) Invoke the CondFrmt dialogue box and create a new rule based on a formula. 4) Type this in the 'Format values where this is true' box, adjusting of course for your column: =NOT(ISBLANK(A1)) 5) Adjust the Format to this: on the Number tab select Custom and in the 'Type' box put this, including the two double-quotes: "P" and then choose any other formatting you desire. This process will check to see if each cell has anything in it, and if it does the number format that will be applied as an uppercase P,which is the ANSI code for the Wingdings2 character checkmark.
Two) 1) Somewhere irrelevant on the spreadsheet execute the following on the ribbon: Insert | Symbols | Symbol. At the bottom choose Unicode (Hex). At the top choose Font Normal text, choose by gliding Subset Mathematical Operators, click on the square-root symbol, click on Insert, click on Close and press the Enter key. This will put the symbol on the spreadsheet. Right-click copy. This is the symbol for square-root that resides within the character set for a normal font, probably Calibri or Arial for you. 2) Leave the entire column or relevant range as-is regarding the font. 3) Select the entire column or relevant range. 4) Invoke the CondFrmt dialogue box and create a new rule based on a formula. 5) Type this in the 'Format values where this is true' box, adjusting of course for your column: =NOT(ISBLANK(A1)) Adjust the Format to this: on the Number tab select Custom and in the 'Type' box put this: “ then paste then “ [it should look like this “√”]. Then choose any other formatting you desire. This process will check to see if each cell has anything in it, and if it does the number format that will be applied is a square-root symbol, which looks close enough to a check-mark to fake it, especially made bold and italics.
