Filter Multiple Date Columns in One Slicer

Hi guys, 

I am trying to solve this for a while and couldn't get a solution. I work in recruitment and I have to make daily/weekly/monthly reports on the recruiter's activity. I have 45 columns in Power Bi full of date/time that describe an action that was made by a recruiter, for example, if a candidate passes from Test to Interview, in the Interview column will appear the date and time when this change was made. 

This is a simplified sample of what I got, I put colors for each month to be more clear.

And this is how 2 of the columns look in reality. 

Can I make a slicer that would filter every action that was made between 2 certain dates, in all the 45 columns?

For example, in the simplified version, I want to see how many actions have been made in January (gray), or February(green) in each column, by each recruiter?

In my real report, it should display something like this, here I used as reference one column of dates like "Candidate Submit Date", but it doesn't give me a real-time activity of recruiters as if a candidate submitted a month before I set up a date in a slicer, the activity for that specific candidate will not appear, even though he passed through some processes between the dates I choose and it's a faulty report.

The reason I insist on the slicer method and not a formula is that I want all the recruiters and recruitment managers to be able to use the slicer themselves and export the data they need without my assistance. 

If you have any ideas or need further information, please let me know. 

Thanks a lot for your assistance!