Im entering the info on sales of my ESPP stock. It requests "date of purchase", this was purchased monthly over many years. how do i enter this?

I assume that you are entering the sale using the "default" 1099-B input form - not the ESPP step by step process - and correcting the basis for any compensation income created by the sale.  I'll also assume all the shares sold are sold in a Qualifying disposition.

If all that's correct then you can simply use the word "various" in the "date acquired" field.

Tom Young