Conditional Formatting Quarterly Meetings

[SarahBevan]

Hello,

I am using a Gantt chart for a project and need to format in quarterly review meetings with conditional formatting. I did find a formula here for biweekly events but haven't had any success editing the formula for dates vs days of the week. I haven't got much experience with Excel unfortunately. The current project schedule just uses a colour fill for the cells. I am wanting to highlight a single cell on a recurring basis. I hope that makes sense eg every 90 days ...

Thank you in advance

 

[SarahBevan]

This is what it looks like, sorry I need permission to download the add-in

 

[SarahBevan]

Surprisingly I appear to have a solution.

I used a n'th column formula =MOD(COLUMN(),90)=0 and then restricted the formula to the single row that applied in the gantt chart. It's probably not perfect due to the weekends but it will do for now.