How to automatically assign a number determined by the rank in a series of dates ?

I'm sure it's trivial for you excel wizards but I haven't found a way to do this yet : I need to generate a number in column A that's a function of the chronological order of the corresponding date in column D, ie the earliest date gets "1" and so on (this spreadsheet is completed on the fly so the column D is manually updated with the date when the customer sends me what I need, so the column A stays blank when there's no matching date, for which I'll just use a IF() function), see pic : https://tmpfiles.org/25810180/screenshhh.png

I googled quite a bit and still haven't found a function that does this.

I use office 360 though not the latest version.

Sorry for the broken English !