I'm not sure what your question is.
I guess you have put YEAR in the color shelf to get the three lines. That's a good way to go.
Do you want your graph to chop off the lines at the last current-year date in your data? (Chop off the other two years as of October 3 as well, and end the chart as of today.) Or maybe you just want to chop off the current-year line so that you don't get a straight line from today to the end of the year.
There are a lot of things you can do with this. If you upload a sample workbook I can work with you to do some of them.
I have testing year (group) on the color shelf to identify the 3 lines.
My goal is to have the graph end at current date and get rid of the long trailing orange line for all future dates.
I've added both a discrete Month and Day to the columns shelf to get the correct overlay but i still have the long trailing orange line which reflects today's value for each day in the future. I've attempted to add a filter with [Creation Date]<=TODAY() but that doesn't work on the discrete date points I've included.
My requested solution would be either of the following:
1) Cut off the trailing orange line from the viz below so that each day it updates the orange line would grow.
2) Cut off the entire viz each day at a discrete TODAY
It would be easier to show you in a workbook than to describe things without and example.
I've done both the solutions you've suggested. For instance, I'm guessing (I have to keep guessing without a workbook!) that you're doing a running sum of some sort to generate the lines. Your running sum for the current year can force a null when you are at a date past TODAY(). That would end the line at TODAY().
Likewise your running sums for the prior years could force nulls when the date is greater than DATEADD('year',-1,TODAY()) and less than MAKEDATE(YEAR(TODAY()-1,12,31). (And the same for -2.)
DATEADD adds the specified time period and the specified amount to the date given. So -1 says to add negative one year to TODAY. And MAKEDATE makes a date value from the given year, month, day. So those two chunks of syntax used today would act on dates from Oct 3, 2017 through December 31, 2017.