Conditional Format

[surkdidat]

I know this should be simple, but my head won't work this out!
In Row 1 I have months
In Column A I have dates of work started
What I need is conditional format to "grey out" the cell if the date in column A is before the start date of the month

So if the date was 02/04/19 it will leave the April column blank,
if it was 2 May 2019, it would grey out April, but leave May 2019 blank,
if it was June, then both April and May would be greyed out etc.

	a	b	c	d	e
1		APRIL 2019	MAY 2019	JUNE 2019	JULY 2019
2	03/04/19
3	07/05/19	(GREYED OUT)
4	06/06/19	(GREYED OUT)	(GREYED OUT)
5	01/08/19	(GREYED OUT)	(GREYED OUT)	(GREYED OUT)	(GREYED OUT)

 

[Fluff]

What are the actual values in B1,C1 etc?

 

[surkdidat]

These are purely column headers with the dates of the month. Effectively they will be 01/04/19 01/05/19 01/06/19 etc

What are the actual values in B1,C1 etc?

 

[tyija1995]

A custom rule would work, highlight the region you want to apply to then open a new CF rule and put:

=AND(MONTH($A2)>MONTH(B$1),YEAR($A2)>=YEAR(B$1)) --> Format with however you choose (greyed pattern style would be ideal under fill tab on format cells)

EDIT: Taken into account of the year too incase month piles over to following year.

 

[tyija1995]

Apologies, that doesn't quite work as intended after some further testing...

Try:
=AND($A2>B$1,OR(MONTH($A2)>MONTH(B$1),YEAR($A2)>YEAR(B$1)))

 

[Fluff]

Select B2 to the end of data & use
=$A2>EOMONTH(B$1,0)